Never mind. After another hour of reading 50 more entries, I found this, and it solved my issues.
I had the same problem (running snow leopard 10.6.3 on Macbook Air). Events i created on non-shared, non-synced calendars could not be deleted or if they could they'd pop up again in seconds. And send me email reminders every 10 mins. VERY ANNOYING.
Tried many things but what finally worked for me is:
go to prefs.
uncheck "Enable syncing on this computer" (it may take a while for this to go from grey to black and let you uncheck it)
click "reset sync history"
go to ical. delete events.
click "reset sync history" again.
RESTART. This is the part that made the whole thing stick.
macbook air, Mac OS X (10.6.3)