Run this and post the link it gives you.
Win 7 Pro on a system with plenty of RAM & Storage keeps hanging/freezing at various time and in odd situations leaving the background of the screen white. This also happens when going from App to App and within Apps. Today I had switched out a Browser and opened my eMail. I could type out a new message, but not send it. I re-booted the system and all three messages went through then without a problem.
Also I get no action when using a link out of an eMail that should ope a Browser. And, I had problems downloading files using direct access to the Software's actual Web Site. Again, shutdown and reboot allowed access - eventually. Downloading a fresh copy of Thunderbird also produced some odd results. The file downloaded, however, it was renamed "file" and would not install. I finally found a Thunderbird Download file on CNET that did work.
Does anyone have any ideas about what this might be? Ran Avast, MalwareBytes, and SuperAntiSpyware - and all came out clean, no bad stuff found.