It's the monitor. Edge-focus is notoriously tricky on flat-screen picture tubes. I have not found anything on adjusting the focus for this model. A quick check on the web indicates that you are not alone, though it seems to be more of a sample-defect problem rather than a poor design; a replacement should be OK. As a former monitor repairman, I have no problem recommending Samsung as a brand, in general.

Thanks for your help, I just wanted to make sure I wasn't going crazy since I have already taken back one of these monitors that had blotches in each corner. I guess it will take just one more trip to best buy.

KLEJ,

TallCool is correct. A replacement is required. It's unfortunate you have to do so and even more so that you already have once before... but faults such as that are trickier to find at manufacturers quality inspection stations, and are frequently passed without anyone knowing the wiser. You just happened to luck out and get the 2 out of 500 (just an example) that are expected field failures. Perhaps someone is testing your patience?