I have a Windows XP Pro SP3 PC which has developed a strange problem - I think after installing a number of Microsoft updates recently.
The PC hangs when it is trying to restart - i.e. as is necessary in some software installs or if you select the "restart" option from the "Shutdown" menu. However, if you let the PC shutdown and then press the start up button it will boot successfully.
The "hang" occurs during the POST sequence immediately after it has tried to boot from CD (which comes first in the boot sequence) and before the loading Windows screen. After a long pause it eventually reports "Boot disk failure - please insert System disk".
So the problem seems to be that it cannot boot from the hard drive C when it is re-starting but has no such problem when doing a normal start up.
I cannot use "system restore" to recover a previous installation because this requires the PC to do a hot restart. I would really appreciate advice from anyone who can suggest a solution.
Something has corrupted the bios I think. lotvic's suggestion sounds good but either change the jumpers to reset the bios or remove the battery, wait for about 30 seconds, and replace. This will reset the bios to default.