Help with Photoshop Unknown Problem(Exact Details explained)

ok so im currently using adobe photoshop cs3 extended i have the entire master collection installed and i will go on here to list as much information as possible about the problem i am having. im currently a waller(makes backgrounds/wallpapers) for an anime site and im working in graphic design so i hope to get this issue resolved and am willing to cooperate with whatever means necessary.

ok so the main problem is that lately ive been working on a wallpaper for my site and just recently the program has been acting up. the best way to describe it is normally the marquis tool when you pick an area the line showing the border of the marquis moves kind of like an animation right? well in my case it works normally for a little then a little later(1-2minutes) the marquis stops moving. at the point that this occurs i can no longer see the marquis but can still move it with the move tool. i can see the marquis if im using the maruqis tool and switch to another tool then click on the image area. also when i try to show/hide a layer at this point when i click the eye it goes away but you can not see the physical changes until i click somewhere in the image. now once this "problem" occurs and i try to exit photoshop the file will close, but photoshop itself will not, then i get an error message saying its not responding and i ahve to manually shut it down via task manager/ rightclick-close multiple times.:mad: i have normally been able to run windows media player, my antivirus download updates, and sometime other programs on top WHILE running photoshop cs3 extended and it normally doesnt have any problems.:confused:

now the file size i am working on is a psd amounting to almost 8mb. and it seems that high files like that seem to give it trouble so i thought maybe the ram access was a problem but i allowed the program under preferences 1.6gbs of physical memory to itself and it didnt change anything. also on the file i was using i was using alot of gradient filler layers to get my effect if that helps. i thought maybe something was wrong with photoshop itself as i have come into contact with viruses occasionally and somehow i had managed to get the frmwrk32 trojan that just recently was discovered but i fixed all those problems so after uninstalling and reinstalling photoshop it did not fix the problem.if its possible a key or something got deleted i can work towards that as well.
for now small files like jpegs under 1mb seem to load and i can work on them vigorously but i have yet to fully try out the memory method. i can provide the exact files i was working on in psd psb or any format necessary to help with this process.

for computer system records this is my info.
im using-
windows vista 32bit home premium SP1
model hp pavillion dv67000(special edition)
amd turion 64 x2 mobile technology tl-60 2.0ghz
3gb ram
nvidia geforce 8400M gs

I can provide any other information necessary or provide my files as well as test theory's. i hope to get this back up soon asap without ahving to reset factory settings or anything drastic. i thank you all for any help and i will cooperate as necessary thanks!

My guess is that you have problems with your computer. That is not a PS issue for sure.
8 mbs file is nothing to phstoshop, I often work with +60 mbs, and for printing industry the files are even bigger. Maybe you need to reset your system

so would you suggest resetting back to factory settings and reloading everything? i mean the computer itself runs everything else fine but i notic ephotoshop only takes up 140,000kb of ram and im not sure why this is my dads going to look at it but i still cannot figure it out