|"i have to turn my netbook on off then on again or it wont come on properly"|
You need to provide a lot more detail about that.
"i dont have a cd drive so cant reinstall windows xp easily"
You usually DO NOT need an XP CD when the netbook originally had XP installed on it to re-load the original contents of C.
In most if not all cases, you cannot install XP from an XP CD in a USB optical drive in any case.
See response 1 and 4 in this.
The same or similar applies to your netbook.
NOTE that Acer often also has a set of Recovery disks you can buy from their web site....
Scroll down a bit.
Accessory Store - click on eRecovery CDs
....or if they no longer have that available, try looking here: