UNDO MANY TIMES PLEASE

Hello, I've read the FAQ but the problem I'm facing right now isn't listed. I've been using PS CS3 Extended for a while now and I'm really happy about it because I downloaded it for free and it's really amazing. But now it gave me a problem and it's kinda weird. I'm trying to hit UNDO (Ctrl+Z) and it's working. But when I hit ALT+CTRL+Z which is STEP BACKWARD (it's just like Undo many times right?) it just won't work. So I can't Undo many times like I did before and it's pissing me off. I had to go through the whole process or copy palettes to another layer just to get what I want. So yeah.. Please please please, someone help me 'cause I'm dying D;

Thank you in advance! :D

EDIT: PROBLEM SOLVED THANKS TO runawaytomars