I have the exact same problem with my HP (a530n). Installed everything the
manufacturer requested, then installed SP2 from a Microsoft SP2 CD.
Everything appears to work fine, but the computer hangs when restart is
selected. If I turn it off, then turn it back on, it boots perfectly. The
RESTART option is the only thing that is apparently no longer working. The
screen goes black (LCD monitor) and the HD light stays constantly lit, even
though the HD is not active. A friend of mine has the exact same system with
the exact same problem. BTW, the bios has been updated and all drivers are
updated. IT IS NOT A VIDEO CARD OR MONITOR PROBLEM.
I'm really surprised that so many people are having this problem, and no
simple solution is available (yet another MS patch, or something).
Re-installing or manually modifying OS files is not a simple solution.
Can anyone help with resolving this problem?