So here's the set up. I've had Win7 ultimate for a bit over a year now i THINK (June/July 2011) and it was my thought/understanding, at least back in XP days, that reformats were only needed 1) when needed or b) if 2-3+ years have gone by). Figured I had another year, as it were, even/especially with Win7. Bro's friend is telling me "nope, 1 year sounds bout right". Course he LIKES to reformat, and he has the space to easily back up cause he's not running 4 HDDs with 2 filled with steam games x.x (also tells me I cant/shouldn't play/be able to use steam after reformat even though its on a secondary HDD with no OS files and it isn't getting reformated....which is weird since one of the hdds came from my friend, filled with video files and games already installed on it and i had no problem with any of them on this system...) Anyway problem: Mice are being inaccurate. I figured it was just my G9 dying since it was 3.5 years old....but then I noticed the problem with a newly bought Taipan (which I returned cause it also gave me some cramping in between thumb and index due to how i had to hold it). Got a G500 for the exchange yesterday...and the problem is still there. The G9 and G500 are pretty much fine on my friends laptop when I tested, too! Also, I noticed I had to move my hand and mouse a bit more and more to get the G9 or g500 to cover the same amount of screen that the g9 used to cover with only 1200 (level 3 for me) DPI...Then I noticed I had to put g9 to 1600 (level four...which I like NEVER had to use) to have it cover. The g500, however, feels/seems to only move a bit too slow or way too fast for the settings I had it on. The best way to describe it is as being a mix of visual and a 'feel' regarding how much I'm seemingly having to use the mice. For small, precise movements, it feels inaccurate and always goes a bit over or too short when the movement I'm doing before would've had it exactly where I needed...even when I slow myself, I still feel/see the problem showing when it overshoots or undershoots or skirts around where I'm trying to point it towards. For longer motions it's remained relatively consistent, though recently, at least on g500, I've noticed it erratically moving a bit too little or overshooting a bit too much (such as in LoL) and making the screen pan when I didn't want it to.... I really first noticed it on minesweeper because I usually do a 40 mine (intermediate/medium) level game in 58-72 seconds, and I go pretty fast for the first 30-35...but ever since this issue started, I've noticed it not going to the exact square I want it to, when before I would've had no problem getting the cursor to stop on the square I want. Something my bro's friend tells me could be the cause is what my friend (the one who gave me the HDD) did to help me clean my computer (and he says he does it for his computer so thats the only reason I let it happen)...he used an electric air duster/compressor (high powered), which my bro's friend is telling me could've potentially broken something or maybe even blown oil somewhere which could cause these problems (and account for the delay between cleaning and start of the problems since it could've taken some time to become an issue) Oh and just to mention, I'll be trying these mice on my brother's set up hopefully later today, so I'll be testing them on a second desktop instead of a laptop. If I cannot find/feel/see any issues on his like I do with mine, I'll certainly report it. It's just becoming more and more aggravating over the past 4 days to have these problems with various mice, have the inaccuracy/sensitivity problems persist, and now I've got the worry of a broken set up (with no idea what is/isn't potentially broken/breaking) and to top it all off...my mice seemed to work relatively fine on a laptop, and even the standard mouse my grandmother uses felt more responsive and accurate than my 'high quality gaming mice' did on my own gaming set up! Any thoughts? Suggestions? Help? Sorry if it seems a bit rambley just trying to get this fixed...Don't wanna reformat if I don't have to, and I'm frustrated after having bought two different new gaming mice and having both, as well as my old one, all show the same issue :/ (Not to mention the weirdness of the two mice since they're no G9, but that's neither here nor there lol) EDIT - Oh and to clarify, this issue started like 2-3, MAYBE 4 weeks ago...and seemed to get progressively worse/more inaccurate as time went on, then it leveled off...and now it's seemingly started getting a bit worse again (Since I've had to increase dpi levels just to make the same amount of movement cover the same amount of screen 'ground' as before) EDIT - Oh, and my system specs listed on site are out of date for some parts. I'll attempt to get the exact info/models and update it in a few hours.