Problem updating Adobe Flash Player

I'm sure there's a simple solution but I can't seem to find it, so hoping you can help. I tried to update Adobe for my friend because the newest games won't play on her PC. It will download but then fail to install with the following error message: "Error 1402. Verify you have sufficient access to that key or contact your support personnel." It's a personal computer and she is the only authorized user. Any suggestions please and thank you?

The page below refers to Acrobat Reader - but, several similar threads point to it for Flash -

Error 1402 | Error 1406 | Acrobat, Reader

Thanks for the quick reply. I tried most of that already from another help forum, but I'll try the instructions from Acrobat and see if it helps. She had some very nasty malicious code last month and I think it may have corrupted her registry. I reset her computer to a restore point that preceded the virus scan scam but one of the registry files for the administrator might still be corrupted. It's worth a try.

Following up on the problem and solution: I had tried most of the normal fixes (removing and reinstalling, etc.) and nothing worked. However I went into the forum attached to the link InlandAZ kindly posted and found another person who had problems with Adobe after contracting the AVG 2011 virus sweep scam. That poor person went through endless instructions from Adobe for diagnosing the problem until the end result was that the virus had altered a registry file. Fortunately Adobe had created a kill-bit that once downloaded fixed the problem immediately. Hooray! Hope nobody else suffers this problem, but if you do, follow the link to the forum and get the kill-bit that corrects it.