E510 camera. Why does it take 30 seconds to focus?

That's because you are using auto focus. That system needs light to actually focus. When it's lacking enough light it uses the build in flash to create enough contrast to focus the objective.
Solutions :
- change to manual focus (mf)
- mount a external flash: then a different method to focus is used
- use a small pocket lamp (the light it produces fades away in the flash)

The first answer is from some one who obviously is not familiar with Olympus (and many other brands of DSLRs) or he would know that many lenses do not have manual focus scales to use. Olympus Standard Grade lenses do not include a focusing distance scale.

The more important issues for you are determining -
1) Are you trying to use "Live View" to focus?
If so you are using a less sensitive auto focus mode. One of the benefits of using a DSLR is that it can use more sensitive auto-focus systems than Point

1) TAKE OUT YOUR LAPTOP BATTERY
• 2) REMOVE YOUR AC ADAPTOR CORD, that's the wall power, remove it.
• 3) NOW HOLD DOWN THE POWER BUTTON FOR 30 SECONDS.
That will drain any static electricity that has built up on your laptop system board and many times fixes the problem of a black screen. After the 30 seconds re-connect your laptop to the wall power and hit the power button normally and see if the laptop comes back up.
4- Replace your battery.
5-Restart

Your camera wants you to format the card in the camera.

if the power button was blinking amber, unplug your tower, and hold the power button for 30 seconds to 1 minute, to use any excess power stored in the capassitors in the pc. this was told to me by a dell tech, it is a small issue with the 3100=E310, and 5150=E510 Dimension desktops

will watch this post have same problem with focus especialiy indoor flash shots. a lot out of focus

See my possible solution at the posting by kawbene of Jan, 18, 2009 which starts out "Fiji finepix e510 won't turn on... Good luck.

If you are in a low lit area with the camera dial set to Auto the flash will do a strobing type of flash trying to help allow more light into the scene. This is called the AF illuminator function. To just go ahead and take the image, put the camera dial to P (program Auto) go to Menu - go to Wrench 1 tab - then right arrow over and then down arrow to AF Illum - right arrow and turn this function from On to Off and then take the image in the P mode setting. No flash flicker should occur.

http://reviews.photographyreview.com/blog/olympus-e-510-pro-review/

try this site.

Please be informed that the [Firmware Version 1.01 for Optio30] has been released. Changes of the Version 1.01 In very rare case, the Auto-focus system may be malfunctioned at the [Flower], [Food] and [Pet] mode. This has now been corrected. This does not apply to the ther capture modes. Follow link below for more information and to download the firmware. http://www.pentax.ca/support/cs_softwareoptio30firmware.php