Stripes appear

[estrica]

A friend of mine is using KaraFun 1.18 and she has some problems (I think it's videocard related, but not sure).
http://port70.net/~estrica/striped_karafun.png <= This is the way it appears sometimes.
Her computer's stats are:
Processor: Intel(R) Celeron(R) CPU 2.66GHz, x86 Family 15 Model 4 Stepping 9
Memory: 512 MB
Videocard: SiS Mirage Graphics
I think she has Windows Vista (looks that way on the pic).
Do you have any idea what the problem might be? Thank you very much in advance!

Update: Was wrong about the op, it's Windows XP