I have a Acer Aspire

This is caused (thats all I know at the moment- the CAUSE) by a process in your VISTA that stuffs up and just hangs there.

Now to solve this one is quite tricky. I can remember we had to do a backup reload on a similair machine just because there wasn't a fix. So I'll just TRY to give you a solution that might fix this...

First, you could try an automated Windows Vista Repair:
if you boot from your windows Vista DVD, it should give you an option to :Scan for faults and automatically repair them. If That doesn't solve the issue try to access the "recovery console" on the Vista Boot up CD, and try a "chkdsk /r" then a "Fixboot" and finally a "Fixmbr" without the quote.

Ok, you can go into safemode, and you can, in normal mode, acces the device manager right ? So first off you check in the device manager which process uses the most CPU usage or the Most memory usage. It should only be a few processes listed because Vista hasn'nt started up properly. If you know the process, then we can take steps to "combat" it.

Now we know what process is using abnormal system recources. So you go into Safe mode, Start, type "cmd" without the quotes then msconfig. Now you'll have to go to Startup and uncheck the item that was using up the resources.
Apply, confirm and Save changes; then restart.

If there are more questions, please do not hesitate to contact me immediately.

Kind Regards,
Stef