Using command click to select file in lion causes them to open--why?

Question

Lately a lot of routine things have become (for lack of a better word) sensitive in Lion. 
I send an email and in about one in three it sends a duplicate. 
If I am trying to place edited text in an email or word document I cannot get the cursor placed-- instead the whole word or group of words is selected. 
If I try to select text using my cursor (by) it sometimes works and sometimes does not. 
If I hold down the command key to select different documants sometimes it opens them and does not select them.  I can also have a document open (sometimes) when I just select it-- click on it twice. 
I tried adjusting mouse preferences but no luck. 
It is driving me nuts-- anyone got any ideas?

Answer 1

Thanks for the input-- but at this point I do not think so.  The mouse is only a few months old and I am beginning to suspect it may have been one of two things.  The first would not explain the problems I had with Word or the opening (when just selecting on the desktop), and that is the I rebuilt the mail boxes in Mail.
The second is that I stopped having the machine open everything when I restarted and restarted bare bones.  I am now only using apps that I need at the moment and the environment seems to be a lot better.  Thus I am wondering if I had a conflict with something else.  I plan to keep sleuthing and will let you know if I come up with anything.