Or are you using a web-based email system. If so, which one and with which browser?
We'll await your reply but in the meantime it might be worth trying a scan with the free version of Malwarebyte'sAnti-Malware:
http://
(Malware can cause all sorts of strange problems)
Alternatively using System Restore (to take your computer's registry back to a date before the problem first occurred) might well provide a solution.
Chris



