unknown hardware problem, Acer aspire 5100

[elp]

Does anyone have an idea about what is most likely the source of the following problems with my laptop?

The problems started with infrequent problems on booting. The hard-disk (sometimes also the dvd-rom) didn't show up in the BIOS. However, after turning on/off a couple of times I usually got it working after some minutes. As time went by this problem occurred more and more frequently (this was kind of annoying, but not a serious problem as I always got it working after a while).

Then one day Windows XP crashed, and when trying to restart I got the message that system files were missing. Actually it appeared that both my partitions were totally unreadable. So I reformatted the entire disk (after reformatting the hard disk seemed fine (no damaged sectors, etc)), and installed Linux. For a few days everything worked ok (however I still had the booting problem). Then more or less the same happened with Ubuntu as with XP (crash followed by missing files in subsequent startup). So now I can't start Ubuntu.

When I run memtest86+, it finds a lot of errors.

Could all these symptoms be explained by RAM problems, or is it most likely the motherboard. Or the hard-disk? I'm not really an expert, so any help would be appreciated.

[stroyal]

Welcome to TechIMO!

If memtest86 reports bad memory you can believe it. Any errors are unacceptable.

Bad memory will corrupt your hard drive over time.