Depending how you maintain your PC a frsh install is always good to do over a long period of time, personally I think fixing the problem would be a better choice with the description of the problem. A fresh install is quite time consuming not to mention reloading all your software, applying all your personal tweaks, and the numerous XP critical updates that must be installed again.
I would begin with making sure your virus scan is updated and run a virus check.
I would then do a check for spyware, if you don’t have any, you can download the free programs of Adaware and Spybot, they do a decent job.
If that hasn’t corrected the problem I would disable all my startup programs.
To do this, go to the start-run box and type in "msconfig" without the quotes.
In msconfig click on the startup tab. Make a note on what programs are checked there.
Next click disable all, then reboot. If this corrected the problem, go back into msconfig and enable the programs you had checked ONE BY ONE, after enabling one at a time try to isolate which program has caused it. Solution would be to uninstall that program, then reinstall it and hope something was corrupted in that program, if not it may be in conflict with other software and I would remove it permanently.
Last thing you can check is the following:
Go into control panel, double click on Power Options icon, click on advanced tab,
on the bottom you will see "when I press the power button on my computer make sure it displays “shutdown”.
In the hibernate tab verify that the hibernate tab is not checked.
In the general tab, if checked, try changing the settings of the 3 options to “NEVER”,
they are turn off monitor, hard disks, and system standby.
Good luck, hope one of the suggestions corrects your problem.
Edited: Forgot to mention one more thing, if you have Sytem Restore active you can try to restore your registry to a time before you encountered the problem. Restore does not always work since depending on the software added after the retore point retore may come back with a message stating it’s unable to Restore. I have Retore disabled and rely on Acronis True Image to get my system running again, it’s my most treasured software I own.