bad mobo?

Still haven't got new PC up and running, so of course old #1 is acting up...
Been getting random "no disk" error messages with some programs, and recently installed CD/DVD drive intended for new rig... seemed to clear that up somewhat.. also did a massive cleanup and defrag of both HDDs in order to complete a big video project...
During that period, i found myself having to re-assign my C drive as the boot disc in POST, because for some reason the PC was looking to boot off the E drive.
Past few days since then, all seemed OK otherwise... then last night I got the old boot failure message, but when I reassigned the drive, it still wouldn't boot. It's on the list, but won't boot.
Installed XP on the E drive, got the system up and running, and all files on the C drive look OK. No apparent hardware issue there.
BUT... now I can't seem to get my motherboard LAN connection working... that port doesn not appear in Device Manager. Activity light is working, LAN is working (I'm on it now, on work laptop), but I cannot restore my connection by any means I know. Re-installed mobo drivers from the disc, etc... no go.
Tried booting with the C drive disconnected, in case for some reason the port is still associated with the old XP install... maybe I need to delete that partition altogether?
I'm starting to think all of the above weirdness is related to this board... anybody have any thoughts?
I'm hoping to keep this machine working when the new build is complete, so I guess if I have to, I'll replace the mobo.
Been getting random "no disk" error messages with some programs, and recently installed CD/DVD drive intended for new rig... seemed to clear that up somewhat.. also did a massive cleanup and defrag of both HDDs in order to complete a big video project...
During that period, i found myself having to re-assign my C drive as the boot disc in POST, because for some reason the PC was looking to boot off the E drive.
Past few days since then, all seemed OK otherwise... then last night I got the old boot failure message, but when I reassigned the drive, it still wouldn't boot. It's on the list, but won't boot.
Installed XP on the E drive, got the system up and running, and all files on the C drive look OK. No apparent hardware issue there.
BUT... now I can't seem to get my motherboard LAN connection working... that port doesn not appear in Device Manager. Activity light is working, LAN is working (I'm on it now, on work laptop), but I cannot restore my connection by any means I know. Re-installed mobo drivers from the disc, etc... no go.
Tried booting with the C drive disconnected, in case for some reason the port is still associated with the old XP install... maybe I need to delete that partition altogether?
I'm starting to think all of the above weirdness is related to this board... anybody have any thoughts?
I'm hoping to keep this machine working when the new build is complete, so I guess if I have to, I'll replace the mobo.