Help & support centre doesn't respond

XP Home SP2. I've been installing some utilities from a magazine and suddenly had a series of problems with the H&SC. At first it told me it couldn't find HELPCTR.EXE; I found a registry fix that dealt with that. Next it told me that the appropriate service wasn't running, and I persuaded it to run. Now it tells me nothing - I've rebooted after the other fixes, and whether I press F1 in the desktop, click the "Help" entry on the start menu, try to start it by typing in the "Run" box, or double-click on HELPCTR.EXE in C:/WINDOWS/PCHEALTH/HelpCtr/Binaries, the result is the same - no message, a brief flicker of hourglass and then ... nothing.
I assume (rashly) that one or more of the utilities carries responsibility, but I'd rather like to get the H&S Centre running again, so if anybody's had similar experiences and has the answer, please - I'm hanging on your every word!
Thanks in hope.
BrianP.