
Lets look what is virtual memory. Virtual memory is a technique developed for multitasking kernels. Virtual memory is not actually existing memory, so that it is calling "virtual" memory. If a program is very large, then the program will divided into segments in such a way that one segment resides in the primary storage and remaining in the secondary storage. If the segment in primary storage (RAM) is about 115mb, you are working with another software which have 50mb in primary memory (115mb+50mb>128mb). It will crash the normal working of computer. It is called virtual memory problem. Virtual memory problem will also arise by virus attack and memory leak. So you should care anti-virus and make sure that anti-virus is up to date. You should also be care memory leak. So you should observe your system process in task manager and kill unwanted background process.
I think if you care these things you can easily solve this virtual memory problem. If you can't solve this, install more RAM and solve it.