I have noticed that when I would try to run msinfo32.exe that it would launch the Help and Support Center on WinXP.
For those of you not familiar with msinfo32, it will give you detailed info about your system (in a nutshell). It can also be launched from Help and Support Center, Support, Advanced System Information, View Detailed System information.
Well, you can see (maybe) the irony with this issue. Start Run... msinfo32.exe would just launch help and support center.
After digging I found an article which solved the problem. (Link should be attached).
In a nutshell, there is SUPPOSED to be an index.dat file residing at C:\WINDOWS\PCHEALTH\HELPCTR\OfflineCache. If it is missing your only option is to find it from another XP system and copy it there. I fired up a VM and copied it from that and all is back to normal now.
A few months ago, I followed a tip which told how to delete all index.dat files from your system. I did it.
( I have found some rare instances where an index.dat file produced some less than desireable results )
The bottom line here, other than providing you with a fix for an annoying issue is..
BE CAREFUL when performing any so called "tweaks, tips or modifications" to your system as you never know how far down the road it can affect you in a negative way.