Can someone help wth this problem. it did not occurred until  2 days ago.but been working about 2 mounds with acad 2012.when i startup autocad, this message apeers: "Autocad requires 1024x768 resolution or higher to run". when the program starts. it looks like it uses a resolution of 800x600.i can not use autocad poperly, i can only close acad with alt+f4 keys i use is 1920x1080, so whats wrong?

Select your AutoCAD desktop icon, pres Alt+Enter and look in the Compatibility tab. You might have the "640x480" option checked by mistake or as a practical joke...