I encounter sometime similar before with my ACER aspire 4736G, so I know how frustrating it is.
Some of the symptoms I noticed:
1) the screen fades to white whenever I furiously click my mouse to get it working (especially when I open multiple tabs)
2) when typing words, the clicker would disappear and I have to wait sometime before the words appear
3) the machine seem to produce lot's of whirling engine noise, when ever it hangs
4) Takes forever to start up.
I reformatted it and now it's back to normal (you'll lose all your saved files though)
Edited by Benjerry - 9/22/11 at 8:10am