Do you have different monitors at work and home? One CRT and one TFT? On TFT's sometimes moving things appear blurry.. Also a resolution which the TFT is not made for (most TFT have native 1280x1024 support and other resolutions look blurred!) makes things appear blurry...

When the sprites look correct on one PC and not on a second one, I guess its the monitors and not your code.