Guidelines for troubleshooting high interrupt rate

"Do you have a USB device connected (besides the
keyboard/mouse)?

I experienced a similar problem to yours, but only if I
connected a USB hard drive. The system would then go into a
state that required a restart to get it out of. Even if the
USB drive was unmounted the interrupt rate would still be
high and the system was slow and not very responsive.

I tried all sorts of things, including removing the USB
devices in the Device Manager and updating to the latest
drivers. But nothing helped. In the end I bought a new
computer as it was time to get a new one anyway. The USB
drive was working perfectly on the new system so it was not the
source of the problem.

I suspect it was either faulty hardware or a corrupted
Windows installation.

In general I don't like to propose unspecific measures, but:

perhaps a first step could be to install Windows XP on a
second empty hard disk and see if the problem goes away. If
it does not then you can rule out a corrupted Windows
installation or a corrupted file system (as it was installed
on an empty harddisk).

Using this method you can return to your old Windows
installation without the need to reinstall applications,
etc. The second Windows installation can also be used as a
backup installation if the first one fails - this can be
very handy if you don't have time to fix the problem, but
just want keep on working. (I also use it to switch back and
forth between a 32 bit version and a 64 bit version of
Windows - although a virtual machine would probably be more
handy)."