Here are the specs for your machine. Acer Aspire 5100
and here are the Acer Aspire 5100 FAQ
Can you identify your problem with any of those mentioned in the FAQ?
Do you have the latest drivers installed? Acer Aspire 5100 Support
(You might have to go through the menu to get to the 5100 drivers).
Have you checked Windows Event Viewer for clues? The system logs events both good and bad whenever it's in use. To access Event Viewer, click Start, then Run (or hit Windows logo key + R), type: eventvwr.msc
and click OK. Problems are identified by either a black exclamation mark inside a yellow warning triangle, or a white cross inside a red circle. If you find any, please post the Event ID(s) for these. The Event ID# is visible in the sixth column from the left after opening a submenu.