Newly installed TB on Windows 8.1 64 bit computer misbehaving

Question

Downloading is generally fast, but stops unpredictabily. But worse, if I try to delete or open mail, TBird usually freezes and tells me it's "not responding". I tried uninstalling and reinstalling twice, and what comes up is always what I had previously installed, even though I deleted everything associated with it as well as uninstalling it. Any ideas what may be going on and how I can fix it?
Thanks,
[email protected]

Answer 1

REVISED AFTER TALKING WITH INTERNET PROVIDER
It's McAfee, which is supplied by my server, shaw.ca. In fact, I posted a response last night that didn't get recorded somehow, saying that I tried turning off McAfee's "real time scanning" since this was off when I was in Safe Mode, and this seems to have solved most of my TBird problems. I spoke to the tech dept at shaw to ask if this is safe to do, and after trying a couple of things (including re-installing McAfee), I was told just to leave real time scanning off and up the frequency of scheduled scans.
THE BELOW PROBLEM SEEMS TO HAVE DISAPPEARED AFTER REINSTALLING MCAFEE:
Also TBird apparently didn't like the fact that when I set it up, I changed the default choice of IMAP to POP3, since that's what I've been accustomed to using, and now: 1) every time I ask it to get messages, I have to reaffirm this "exception", since TBird claims this isn't valid. 2) there doesn't seem to be any way I can change back to IMAP (shaw tell me that either is okay for them) from within TBird now...
Now back to my life.... : - )