File corrupted, network, flash drive

Hi
computer:
AMD Atloh 64 / 3000+
512 MB Ram
250Gb disk
Gigabyte GA-K8-NMF-9
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When I install XP SP2 i got some error that driver for disk and cd aren’t present.

Now I’m getting errors with bigger files at installation (SP3, some programs) file missing, corrupted...
Network was working and stop working after a while, from the start network connections are empty I can open it. Led are blinking for 1 second, then 3 seconds are out.
USB flash drive was working and now its not any more.

I try different disk, different RAM, WIN XP SP3, and different Ethernet card. No change.

HELP