I was just working on a logo and this particular problem was annoying me to no end... Holding shift for 8+ seconds would toggle sticky keys acting as a click to finish out the selection. A real bitch when trying to get some geometric selections by holding shift with the lasso.
The fix! No, turning off all sticky key options in accessibility options didn't help the situation, as they were off but were still registering to windows and causing a "release" function while making a selection.
Go to registry editor, search "stickykeys" and set the "flags" value to 506. BINGO!
Just had to tell someone who may appreciate it.