I just installed Ubuntu on my Compaq desktop and everything seemed to go well. The desktop appeared just like it should...

Only then this happens, seconds later:

Crash

Something tells me that this is not supposed to be happening. I did not partition, I replaced Windows 7 with Ubuntu. When I try to run off the USB stick I used, I get this:

USB

So, what do I do, now? Should I try to reinstall? Is the ISO bad, somehow?

System specs:

Compaq Model CQ5205Y

AMD Semperon LE-1300

2 GB RAM

250 GB HDD