Temporary internet files could harm your pc if the files contents virus, this could also slow your pc because if you have files that was infected with virus specifically the application files. Those files were automatically load into the services and in the processes and also in the start up without your consent. If all these files will run in the system this will cause " a low virtual memory" because the memory speicified was use by these useless and annoying application.
If you encounter these problem i would suggest that scan you computer with a potent antivirus, you should empty the temporary files and the recycled bin.
If you are sure that the computer is virus free and still encountering the "low virtual memory" you can increase your virtual memory by doing these:
1 right click my computer and then properties
2. click the advance tab
3. in the performance., click setting
4. then " advance tab"
5. in the virtual memory click change
6. check custom setting
7. in the initial size double the size of your memory
7. maximum double the initial size you setted.
If these will not solve the problem i would recommend you to format and reinstall your system.