It does not appear that any one of us can help you further without FTP access to your site and CP access to your forums. As well, you might need to give access to your web site's CP.
You do not know me from atom, but if you feel trusting, I can take a look at things to see what's going on. You would need to PM me the access mentioned above.
And just so you know, the OS of your computer is not likely to have a bearing on this issue. In general, baring a virus, the OS of the computer you use to access your site cannot cause a problem such as this.
I have some time this evening, and next. Up to you. Free of charge. No promises of a fix, but I will not make it any worse either.