I don't have any actual problems with my Cintiq. Occasionally I'll need to recalibrate the pen but that's about it. Can't use it as a dual monitor however which is a massive drawback and also part of the reason I purchased it.
I suppose I've minor tracking problems but that's really just towards the edges of the screen, so it's become a habit to drag whatever bit I'm working on to the center of the thing and use the edges for viewing space only.
On occasion it refuses to detect marks by way of the cursor freezin, but I find that a quick touch of the eraser end of the pen to the screen unsticks the cursor, which is a fairly rapid solution!
B'yeah, it's made me quite color-paranoid/confused, between the Cintiq and a lower end macbook. I have no idea what colors I'm using exactly anymore. (this could be some sort of philosophical comment on perception and reality, I suppose)
Hm, I'll definitely have to try the eraser trick. Occasionally I'll get spots that don't want to work on the screen, but they come and go.
Color matching is also a problem - I've got it hooked up to a PC, and even though I can match the profiles I get totally different contrast on the PC, Cintiq, and MacBook screens. It drives me nuts. I feel like I need to create the profile in my head based on the color tone selection boxes, and screw what all the screens say hahahaha.
Yeaah it is a huge pain. I especially have weird issues with blues looking purple on the mac, or lighter shades looking positively florescent. 's either that, or get a pantone swatch book and colorpick religiously! The once where I actually had to print my stuff I almost died, oy vey. To think in pre-cintiq days I naively assumed (subconciously, at least) that everyone was seeing what I was, heh.
I've had the vertical lines issue with my regular tablet, and 'jumping marks' so it could just be the thing wigging out. Ever since I went from 2000 to xp I suddenly started having issues with tablet significantly more often (as well as photoshop). Maybe it's an issue with the age of the cintiq/program driver vs age of OS?