Well runtime error is an error that occurs during the execution of a program. In contrast, compile-time errors occur while a program is being compiled.
Runtime errors indicate bugs in the program or problems that the designers had anticipated but could do nothing about. For example, running out of memory will often cause a runtime error.
Make sure you have enough memory for you to use the program.
Also make sure you d/l the latest audacity which is 1.2.3
http://audacity.sourceforge.net/download/