Un wanted watermark

How do I git rid of a watermark logo that suddenly appeared on my computer screen, it's 2 objects about an inch tall, one sort of looks like a fish hook the other looks like a cap to go over the hook (not a good definition of objects). They do not print when page is printed. I have run "System Mechanic, Malwarebytes, McAfee Security" on the computer and its still there.

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows XP Home Edition, Service Pack 3, 32 bit
Processor: Intel(R) Core(TM)2 Duo CPU E6550 @ 2.33GHz, x86 Family 6 Model 15 Stepping 11
Processor Count: 2
RAM: 2046 Mb
Graphics Card: ATI Radeon HD 2400 PRO, 256 Mb
Hard Drives: C: Total - 40970 MB, Free - 12852 MB; D: Total - 197392 MB, Free - 197265 MB; F: Total - 476937 MB, Free - 466722 MB;
Motherboard: Dell Inc., 0CU409
Antivirus: McAfee Anti-Virus and Anti-Spyware, Updated: Yes, On-Demand Scanner: Enabled

Any help would be appreciated