With respect to Internet Explorer 9, when I start it up I get a couple of error messages that concern me. One says something like, "Dropbox is unable to access registry" and suggests that I try a password change. I don't know my wife's Dropbox account information and I believe that problem will ultimately be easy to resolve once the underlying issue that caused this and the other problems the computer is having are resolved, so I'm not overly fussed about the Dropbox error at this point. I've posted it because I suspect it will help to narrow down what might be going on more generally.
The other error reads, "A program on your computer has corrupted your default search provider setting for Internet Explorer. IE has reset this setting to your original search provider, Search Results (dts.search-results.com). IE will now open Search Settings where you can change this setting or install more search providers." I am unable to edit the search providers in the subsequent dialog box.
I can get past both these errors and IE seems to work pretty well the way it did before. However, there is another strange symptom. That is that IE does not seem to be saving any history anymore at all.
I had another strange error message. When I open MS Word I got the following or something very like it: "Word could not create the work file. Check the environment variable." I could close the error and keep working but it happens again every time I open Word.
There's another problem as the PC boots that might be worth mentioning. I get a message saying that "Catalyst Control Centre host application has stopped working." There's a bit more to the message that says, I believe, "A problem caused the program to stop woring correctly. Windiows will close the program and notify you if a solution is available."
So I've got a number of issues all at once that I suspect probably all happened at the same time as a result of a malware attack of some kind. MalwareBytes finds nothing. Avast AV finds nothing. Can you help?