The Master Boot Record (MBR) is basically a place with information stored on it that the BIOS uses to load the initial boot program that starts the process of loading the operating system.
Also referred to as the master boot sector or even just the boot sector.
It is used solely for this purpose, so if your OS is booting ok after you press any key to continue, then it should cause the computer no further problems.
If your system is crashing whilst you work with it, something else is causing it to do so...ie System software confiliction, virus's or other Malware etc.
The MBR, however, is easily fixed if you have your XP install disc handy!
Boot with the XP installation CD. (your BIOS will need to be set to boot from CD)
When prompted, press R to repair a Windows XP installation.
Enter the administrator password if prompted.
To fix the MBR, use the following command:
fixmbr
This assumes that your installation is on the C:\ drive. You will be presented with several scary warning lines the reading of which will make you want to say no. Microsoft is exceptionally vague regarding the conditions under which fixmbr can cause problems although they are clear about the consequences (losing all data on the hard drive), so use this at your own risk.
Type y and ENTER to fix the MBR.
Type exit to leave the recovery console and reboot.
If your worried about whats causing future system crashes, you can send us a HiJackThis log and we can take a look at whats running on your system and helping you to get rid of anything that shouldnt be there!
Regards