OK, to explain this im going to need to explain what ram does.Ram stores files that are currently in use by the computer, because it is a lot faster than transfering all the files directly from the hard driveHowever, the computer doesn't always have enough ram to store all the files, so when the ram space gets below a certain amount, the computer puts the less used files into a cache, or temporary storage part of the hard drive, the computer can use this part of the hard drive as "virtual ram" or virtual memory.So when you had the stick of ram removed, the computer needed to move more files to the virtual ram, but your computer did not have enoughso here i have a question, did this only come up once? if it comes up multiple times, does it say "windows is increasing the amount" or something like that?You can change the virtual memory settings by the following method1. Right click on my computer2. click properties3. Click the advanced tab (xp only, vista users need to click advanced system settings)4. find a section called performance, it should be the first section, click settings...5. in the new windows click the advanced tab.6. in the section marked "Virtual Memory" there is a button that says "change..." click itthere are a few "radio buttons" which are circular buttons, click the one that says "custom size"note the current size and increase it to whatever you think you need (Note 2 things, i think that 512 is default, not sure, you can change it to anything BUT remember that this takes space in your hard drive, keep that in mind, ALSO NOTE that by setting the minimum and maximum to the same number will save CPU time paging the file up and down (speeds up the PC for other things)) so it is always best practice)NOTE THAT THE ABOVE WILL WORKhowever, i recommend you have your tech savvy friend acquire a new stick of ram for you as your machine seems to need it, and this will help your computer to continue to run smoothly!