I'll bet I unwittingly ran a malicious program at some point which has caused this problem. At the same time, my internet connection has become quite spotty, and I'm sure the two symptoms are linked somehow.
My PC is a custom-built system with some high-end parts I just bought in February: Intel i7-920, Dominator 6GB DDR3, ATI HD5870, 80GB SSD & 1.5TB HDD, etc. The OS is Windows 7 Ultimate 64-bit. Let me know if you need any further details and I'll gladly post them.
Edited by SturmB, 23 April 2010 - 07:18 PM.