Ed, I was a bit intrigued by your use of the phrase "at the moment." This
implies that this problem had a starting point. Since my balloons will stick
around as long as the cursor hovers, it seems plausible that you have picked
up a piece of malicious code, perhaps a virus or even spyware. You need to:
1. Update your antivirus protection and scan at least once per week.
2. Download (free) Spybot Search and Destroy and run it.
3. Download AdAware and run it.
4. Let us know if they helped.