Diagnosis: is this machine broken?

[Sandy Harris]

i have a machine -- Atom 1.6 GHz, single core but hyperthreaded, Intel board
and 2 gigs RAM (the maximum supported). A while ago it began giving many
errors, all disk-related, so I replaced the disk.

Now it mostly runs fine and Checkbox (the tester on the Ubuntu system
menus) reports all OK, but there are three worrying items. When I try
memtest x86+ off the boot menu, it fails with a message about
"insufficient low memory". At boot time, there are many error messages
from udevd along the lines of "worker failed to respond". Finally, the
drscheme application is horrendously slow; menus take several
seconds to open.

I wonder if there might be some motherboard or RAM fault that caused
the earlier disk corruption. If so, replacing the disk will not have fixed it
and problems are likely to recur. This is worrying.

What is my next step in diagnosis here?