You could supply more clues and information. Simple maintenance that you've done such as dust out the machine and the rest of the forum note which asked:
Note: If you're asking for technical help, please be sure to include all your system info, including operating system, model number, and any other specifics related to the problem.
This week my computer has begun freezing up randomly, usually shortly after startup. The only thing I have done new is to add the two updates from Microsoft that came out earlier in the week. Has anyone else had similar problems?