Keep getting this message,how can I fix.THANKS

The error 0xC0000005 is generated by an illegal "memory access violation". This can be caused by anything from faulty RAM, an incorrect/corrupt device driver, poorly written/updated software and more commonly under Windows XP Service pack 2, malware/adware installations.
Usually you get this (http://www.updatexp.com/0xC0000005.html#)error message when performing a specific task, and if that happens you need to check the corresponding 3rd party's website/support department to see if they are aware of the problem
..a while back Symantec Antivirus (http://www.updatexp.com/0xC0000005.html#) caused the 0xC0000005 error with an additional message about a file called SAVRT.SYS . A simple software update to the Symantec Antivirus cured the problem.

what is the best way to eliminate problem,who sells best software

a guess would be it started right after you did something like install new hardware or software or you did nothing at all wrong and got a virus or hit with some sort of malware

For software I would first try installing all the Microsooft patches , anti viris software updates and malware updates

maybe get lucky

Were you running disk defragmenter?
This is common and this is a workaround from Microsoft...
WORKAROUND

To use the Disk Defragmenter tool to work around this problem, follow these steps: 1.To start the Defragmentation tool, right-click My Computer, and then click Manage.2.Click on Disk Management, and then click Disk Defragmenter.3.Select a volume to defragment, and then click the Defragment button.4.After the Defragmentation Completed dialog box is displayed, click the Close button. 5.Wait until the Analysis and Defragmentation displays are updated and the volume is enumerated. You may see a Resizing the color image message as the displays are being updated.6.Exit the Defragmentation tool.