Vicki,
I could explain it, but this is actually a good site to read up on them along with how to use error codes.
v5.0.26 had a bug that was causing a runtime error #364 for some users specifically whey they tried to order labs, e.g. Jack above. This became known as 364 and kept a lot of people from either going to that version or upgrading to v5 at all.
For AC to fix these errors, they first have to reproduce it, which they obviously did. Then they had to find a fix. When it is widespread, it is generally do to something wrong with the program that has to be fixed on AC's end. But, an error can happen with a program due a combination of the program and something on that particular computer such as device drivers, etc.
http://windows.microsoft.com/en-us/windows-vista/What-is-a-runtime-error
