Illustrator brushtool NOT displaying brush stoke in realtime... Please help!

Question

Hi
I been a hunting for a solution to my problem for a while now and am desperate to find out why it's happening and how to fix it
When I apply a brushstroke with my brushtool, No stroke displays itself in Realtime until I end the stroke.
And the other weirdest thing is it only on part of my monitor screen (right side) is where it doesn't show in realtime ... the other 2/3 of the screen it does show while doing the stroke action in realtime.
So if I'm doing a stoke with my brush tool from right to the left of my screen, nothing will show until it reaches a certain point on my screen, then from there on it displays in realtime as it's supposed to. Once I lift the brush and end the stroke only then does the full stroke reveal itself. And if I do it from left to right of the screen then opposite happens i.e. ... 1st one can see the stroke in realtime, but then it disappears once my stroke action reaches the specific area of my screen.
I thought it might be my screen, but I've tried on different monitor screen and have the same problem.
SOMETIMES, it works normally and displays itself completely the way it's supposed to, but the rest of the time it doesn't, and I have no idea what's making it behave this way
I'm working on a laptop i7 8gigram, Win7 64bit.
Please I'd really badly like a solution to this problem.

Answer 1

Hi Cari
Thanks for your quick response. I'm using CS6 with latest update (it also happened before the update, was hoping the update would fix it)
I'm using various calligraphy brush tools which again I say seems to display ONLY on the right hand side 2/3 of my monitor screen, it stops displaying at a very clear and crisp area down the one side of my screen.
The files I'm working on aren't very large at all, between 5 and 8 megabytes in size. At the moment I'm only doing "line-art" with no special fills or effects, as I then take the line art afterwards to pPhotoshop for coloring.
However, I have now noticed ... that if I open only one file (5-8mb), it all seems to be working fine, but the moment I open more that one file (even just 2 files at the same time), THEN the problem seems to occur.
So I'm thinking MAYBE it is a memory issue, ... but then again I don't understand why because the files are so small ... I have 8gig ram, Win 7 64bit.
Also regarding the scratch disc ... I made a separate partition of about 50gig which I use as the scratch disc instead of using the "start-up" or same partition that my OS is on ... that should be sufficient shouldn't it for the small size files I'm working with?
I'm not using the "secondary scratch-disc" as I for one don't know how it would effect it, and also if I did would making a nother 2nd partition for this actually be right and would it make any difference?
TIA