I installed 2x1gb modules and windows 8.1 won't load correctly. I get to a blue screen with 5 options. Help!

You may have not installed the RAM modules correctly... check that they are fully seated on the RAM slots.. If possible use a compressed air can to dust the mobo ram slots and wipe the RAM pins with a clean cotton cloth with a small amount of alcohol if possible, and allow a few minutes for it do dry before replacing the modules.

If the 2 modules are different in any way, interchange them on the slots, and if your motherboard has 4 ram slots, install the modules in slot 1 and 2, same color slots. This also applies if you had 2 modules and added 2 more.

Which RAM slots are 1 and 2 and which are 3 and 4 can be determined from the PDF user manual you can download from the motherboard manufacturer website / support / downloads.