I cannot establish a working WiFi on my ASUS A639 PDA

First you have to ensure that the problem is not from the internet connection. Try using the PDA and the same wireless connection to open a different site which is different from the email provider. If the other site opens then you are sure that the problem is from either the phone or the email service provider.
On the other hand if it does not open then this means that the recommended settings which are expected for the PDA to work with the wifi have not been properly set to give the PDA internet access. The device might be connected to the wifi but not connected to access the internet from the device. Try setting up the PDA and this time take care of the settings.
Hope this solution has been helpful?

Please find the following link to be useful to you

Asus A639

I had this problem on my A639 after going on holiday with it (I think the x-ray scanners did something to it). It started switching itself off more and more as the days went by until one day it went off and never came back. After resetting it, it just stayed on the blue "ASUS Rock Solid Heart Touching" screen. I was worried that it was totally broken and I'd have to pay to get it repaired, but after searching the internet it turned out all I needed to do was re-flash the ROM with a fresh copy (I used the latest ROM). It now works fine and no longer turns itself off... didn't cost me ANYTHING to fix :-)

Check out this webpage for more info:
http://forum.xda-developers.com/showthread.php?t=401850

I had this problem on my A639 after going on holiday with it (I think the x-ray scanners did something to it). It started switching itself off more and more as the days went by until one day it went off and never came back. After resetting it, it just stayed on the blue "ASUS Rock Solid Heart Touching" screen. I was worried that it was totally broken and I'd have to pay to get it repaired, but after searching the internet it turned out all I needed to do was re-flash the ROM with a fresh copy (I used the latest ROM). It now works fine and no longer turns itself off... didn't cost me ANYTHING to fix :-)

Check out this webpage for more info:
http://forum.xda-developers.com/showthread.php?t=401850

Hi. You can perform all three steps in this page in order: (http://www.hardreset.eu/asus_mypal_a639_hard_reset_soft_reset_en.html) Hope this helps.

I forgot password for MyPal Asus A636 ? Should I cry or somebody will help me ??? Thank you so much !!!

Test the network capability - ping your card and also do an auto detect through home network set up.
If it still doesnt feature, unplug, reboot phone and replug. shoul;d work!

My Asus A639 is also frozen on the blue Heart of Technology screen AGAIN. None of the buttons work, hold button is not active, cannot switch it off. The first time it was fixed by Asus under warrantee - took 5 weeks. The freeze might be related to using GPS software Copilot V6 - not certain.

Help please - how do I do a total reset?

Happened the same for me.
After lots of digging & googling I found the simple solution:

At the back of the PDA there is a "Hold" button. Change the position back and it starts to respond as usual before.

what kind of connection do you have? and to what? I assume you have an ADSL(high speed) connection to the internet, and are trying to connect wireless to a laptop or something. what kind of devices are you trying to connect together? this will help with an answer.