My Zen vision: M is stuck in hold. Sliding the switch does nothing except make the hold symbol blink when slid all the way to the power on/off position.

check the hold button...is it set to on position..?

Hi:

Look at the power switch at the top. You have probably turned it all the way to the left when you turned it on. It has a locked position to keep it the settings from being changed by acident when it is in your pocket

If a reset does not work using the reset hole, then try this: First, back up all of your music and do this: Turn off the player and disconnect it from the computer. Then press and hold the play/puse button and turn it on simultaneously. The player should be in recovery mode. Scroll down and select format (all) and let it format. Then reload all of music back onto your player and it should work like new. Hope this helps!

You tried these yet? 
Reset, Format or Clean Up a Zen Vision:M

If your player stops responding, you can reset it. To reset the player, push the end of a pin-like object (for example, a pin or straightened paperclip) into the Reset hole. This should not cause you to lose any data or audio tracks, unless you were in the middle of transferring an audio track.

To reset Zen Vision:M to factory default settings:

Press on the Menu/Back button on your player, and select System, and then Reset.

To Format or Clean Up Zen Vision:M

1. Detach the Zen Vision:M player from your PC , and ensure that the unit is off.

If the battery is too low, charge the battery fully before continuing
2. Slide the Power switch towards the Power icon and hold the switch in the Power On position.
3. Push the end of a pin-like object (for example, a straightened paper clip) into the reset hole, press gently and remove.

4. Release the Power switch when the Creative logo appears. The Recovery Mode appears:
* Clean Up (Performs a disk scan on the player's hard disk, it will not affect music files)
* Format All (Formats the players hard disk - Note: all contents will be lost)
* Reload Firmware (Reloads the Operating System on the Zen. Select this option ONLY if there is a firmware available to reload.)
* Reboot (Reboots the device).
5. Select Clean Up or Format from the Recovery Mode, and then select Reboot.

http://dmzweb4.europe.creative.com/...com:80,Case=obj(14048),Kb=ww_english_add
pls rate it, thanks

I was having the same issues with my Zen Vision M : 30 G. It was not recogznized on any computer, and when I turned it on after having it off for a large amount of time (24 hours), it would rebuild half way before completely turning on.
I did a TON of research and found nothing but I finally got my Zen to work by trial and error.  This is how I did it:
Download the MP3 Recovery tool on the Creative Support Website. Make sure that the MP3 player is at least half charged.   Turn on the mp3 player, holding the on power switch in the ON position. (Very important to hold the Power switch!) While holding down the Power switch, reset the Zen by inserting a small object into the hole at the bottom (thumbtack, wire, earring).  A menu will appear: Clean Up, Format (All), Reload OS/Firmware, and Reboot. I chose Clean Up first and this did not work for me so then I Format.  It will remove all of your data on your Zen.   After Formatting, Reboot your Zen and plug it up to your computer. Run the MP3 recovery tool again.   The Firmware should recognize your Zen, and once installed, so should your computer.
I hope this helps!

I had the same issue with my zen vision m. It was not recognized on any computer (although it would charge) and I noticed that when I turned it on after having it off for any amount of time, the zen would rebuild half way before turning on. 
If this is what is happening with you, then this one solution I found to fix it: 
Download the MP3 Recovery Tool from Creative Support website. Make sure that your Zen is charged at least half.   Turn on your Zen, Holding the power switch in the on position (Very Important!). While holding the Power switch on, Reset the Zen by inserting a small object in the Reset hole on the bottom of the Zen (small objects can include thumbtack, wire, earring, etc...). You will see a menu: Clean Up, Format, Reload OS/Firmware, Reboot. (It is now safe to stop holding the Power switch) I decided to go down the list until something worked.  I ran Clean Up first and that didn't work for me, so I tried Format.  It will remove all of your data. Once Format runs, Reboot the MP3 player and plug it up to the computer. Run MP3 Recovery Tool. The firmware should should install itself on your MP3. Once installed, your computer should recognize the Zen. 
I hope this helps! 

have you tried an ac charger?

You can get a new battery.
http://marketplaceadvisor.channeladvisor.com/storefrontprofiles/processfeed.aspx?sfid=92714&i=230057486&mpid=7840&dfid=1

You will also need this guide to know how to take it apart and replace it.
http://www.anythingbutipod.com/archives/2006/02/how-to-disassemble-the-creative-zen-vision-m.php

"If your Zen V is dead, wont respond to anything, try this, plug it in to the computer, hold the power switch in the on position, THEN trigger the reset button, worked like a charm for mine, I had thought it a lost cause."

Q. How to reset Zen v +
http://www.youtube.com/watch?v=22T_gkkZjmM&feature=related

Zen V is dead
"If your Zen V is dead, wont respond to anything, try this, plug it in to the computer, hold the power switch in the on position, THEN trigger the reset button, worked like a charm for mine, I had thought it a lost cause."

Zen Vision:M Not Responding SOLUTION! to No Charge, Device Not Connected or Recognize
http://www.anythingbutipod.com/forum/showthread.php?t=10960