When You uninstalled did you use the mcpr tool in the link above(useful links tab)? You have not had another AV program installed? Date and time correct for locality choosen?
Do the uninstall and run the preinstall tool as well.http://download.mcafee.com/products/licensed/cust_support_patches/McPreinstall.exe
If all no go use the customer service link in the same useful link tab to see if they can assist.
I used the MPCR Tool and the Pre-Installer and it now lets me register, thank you very much for your help.
Glad to be able to help