I've talked about this before in these forums, but have narrowed it down a bit...
WinXPSP3. Dualmon system.
Open HEM 1.09b32. Start Import. Click on cash games, sessions (or something else).
Open an Excel 2007 spreadsheet. Use it for a few seconds.
Switch back to HEM. Click on something else or click refresh.
Result: My icons on my desktop start blinking, I am unable to type (it misses charaters), and it lasts for quite a while (seems to make the query go WAY slower than it would if Excel wasn't open).
If I close both Excel and HEM and reopen HEM, problem is gone.