I have 2 CAD programs in new versions which certify compatibility with Windows 7 x64. Have used earlier versions of these programs on XP for years successfully. Found that I can install these into Windows 7 x64 easily on 2 laptops: one with an i3 processor, 8GB RAM, the other an AMD processor with 3GB. Unsuccessful on main desktop machine, which has an i7 processor and 8GB RAM. At completion on one program (Altium10), or double click start, I get no response at all. On other (Cadence 16.6), the license server balks. Debug log shows it could not write environment variable. Even manual entry of the correct variable yields nothing. Have compared debug logs, environmental etc. - the same disk just will not write the required section, and the programs balk.
Can not see anything in user accounts being wrong so far. In both cases, I call up install with administrator privilege. So WHY would a desktop balk at both?
Yes, have run Norton 2013 and Malwarebytes clean.
Thanks for your comment.