Basically, this utility works like this: you have some files on your computer which you would like to check for viruses ( malicious software ), or anything else which could infect your PC. Typically, these would be music files, movies, or other programs which you may not want to lose. However, what happens if you don't have any of these files on your system - such as because you've recently got rid of them, or they're already corrupted or damaged? Well, with MD5 Checker, you can run a simple program which checks to see whether your computer has an existing MD5 checksum, and if it does, what its current status is.
For example, a virus would most likely leave a small, seemingly harmless (if you only have a small file of the virus) virus, however a large file would give it enough information for the virus creators to rewrite the original file and create a larger, more dangerous worm. Therefore, with a simple program such as MD5 Checker, you can tell how many changes the file has undergone since you removed it. If the amount of data it has undergone is more than enough to trigger your anti-virus programs, then it's good to know that your computer is safe, and no, it's not time to go buy a new computer! However, if the data shows that there were no changes made to the file, then there may be data that needs to be deleted in order to safe guard your system. The best thing to do here is to use a freeware program such as MD5 Checker, and compare the difference between the two files, and make sure your computer is safe and sound!