There are reports of systems being damaged (Add/Remove Programs and Registry damage) caused by installing PC Doctor 5 without uninstalling the earlier version first.

I do not have all the facts, because I have not yet done this upgrade. However, the posts here have an undercurrent of problems that is believable.

It seems reasonable to suggest people wait before upgrading PC Doctor. Do not upgrade PC Doctor until and unless there is information on Lenovo's site that this problem has been addressed in some way.

Disclaimer: I am not speaking for Lenovo, this Forum, its owner and sysadmin Bill Morrow, or anyone else. I have reviewed the posts, and this seems a reasonable short-term conclusion on my part until we know better what to do.
... JD Hurst

Update:

I uninstalled PC Doctor current version, downloaded and installed PC Doctor 5 (manually) and it works fine. I am still following the threads and Lenovo is looking into it, however done as noted, it is working without problem.
... JD Hurst