A call to all you IT savvy forumites...can anyone help me?

Went to go on my PC on Saturday and was faced with a screen giving me the following options:

Safe Mode
Safe Mode with Networking
Safe Mode with Command Prompt
Last Known Good Configuration (your most recent settings that worked)
Start Windows Normally

It advises that if PC shut down unexpectedly, choose Last Known Good Configuration; or if it was due to a power failure or turned off rather than shut down, choose Start Windows Normally.

Whichever option I pick, I am then faced with a 'Stop error' screen (blue screen with some technical information on the bottom). In the case of the Safe Mode options, I arrive at this screen after the PC runs through some lines of code.

The Stop error screen tells me to disable driver if one appears in the error message (one doesn't), or to possibly use safe mode to disable any recently installed components or software. Given what happens when I do go for the Safe Mode option from the previous page (see above) I can't do this.

The only thing I can think that may have caused this was having to interrupt a Windows update installation after the PC froze. It's happened before, and the last time it did, I just turned the PC off at the socket, turned it back on again, and it was fine.

Is this something that a good reboot would sort out (please no, as I don't know where the disks are!!), or are there any other ideas?

In the meantime, borrowed daughter's laptop to write this (work's laptop has Forum sites blocked), and am only left with a PSP to view any responses

Many thanks in advance for all the expert advice I know will come my way...possibly.