Win7 - weird little screensaver glitch

I'm running Win7 X64 Home Premium on my home PC. I rarely use screensavers in the 'true' sense: I don't have a screensaver enabled to run after a period of inactivity (I'll usually just turn off the monitor if I'm going to be away from the PC for more than 30 or 40min). I have a "ScreenSavers" folder on my desktop, and I'll manually launch one of 10 or 15 different screensavers depending on my mood (and each one has numerous config settings -if you right click and select 'Configure'- making it even more unique but that has nothing to do with the scope of this thread). The screensavers I'm taking about are free released under the GPL, and they're totally awesome, and you can download 'em from this link. Anyway . . . . here's the weird little glitch, and it doesn't happen very often: when I go to launch a screensaver as I always do by double-clicking on the .SCR file, it will open for a second, start doing its thing, then flashes to the desktop, then flashes back to the screensaver, then the screensaver closes, the desktop flashes once or twice and comes back to normal, and that's it. No screensaver running, and I'm back at my desktop. Back in January or February, the first few times this happened, I'd reboot and the screensavers would run again. Then I discovered that when the glitch happens, I can simply run the disk cleaner in CCleaner and that corrects the 'glitch'. Weird, no?
:confused

(I guess this isn't really a question, and I'm not looking for a 'fix' because this isn't a big deal, and running CCleaner is the 'fix', but I guess I'm just wondering if anyone knows how/why the screensavers will glitch like this -and it rarely happens- and how/why running CCleaner "un-glitches" it)