Close Programs to Prevent Information Loss. Your computer is low on memory. Save you files and close these programs. Java (TM) Platform SE binary Windows Media Player

First of all, unless you know EXACTLY what you're doing and WHY you're doing it. I personally recommend never doing anything in regedit. I consider myself a moderate to advanced computer user, and moderate user of windows. And I always stay away from regedit if I can, because you can seriously screw things up if you don't know what you're doing.. although to be honest most settings won't have a dramatic of devastating impact.

It seems to me that it is a memory leak in the program, you will get that error message to insure that your computer won't just crash, because if it runs out of RAM.. well it will crash.

If you have a 2GB and a 1GB totaling 3GB, I recommend upgrading  once more and just rounding it off at a nice 4 (This is the most memory a 32bit system can handle total)

The way memory works you really see some performance jumps with Dual Channel Memory, the only way to have that really is to have the same sticks in each slot.

There really isn't ONE reason this happens everytime, except that simply your computer is low on MEMORY, when your computer says memory it means RAM, not storage HDD space.

If you clean your computer of programs you never use, and stop using windows media player (itunes is better in my opinion, even if you dont have an ipod) you may see some improvement, but to really isolate the problem I recommend simply opening up your task manager as soon as you start your computer (ctrl+alt+delete usually gives you the option or opens it directly) alternatively you can do Start-> RUN taskmgr.exe, OR type taskmgr.exe into the search box and hit enter.

Then watch the memory column as I said it sounds like a program has a leak, and you will see which one because the memory will start at low/normal numbers, and then just keep climbing..

Also make sure your computer is recognizing all 3 GB or RAM. in the task manager if you have access to the performance tab, under Physical Memory should be a thing called Total, 3GB=3074. If that isn't an option in yours for some reason, under Accessories/System tools(in the start menu) you can go to System Information. (may take some time to load) but on the main page you should see something that says TOTAL PHYSICAL MEMORY. You obviously want this to read 3GB or 3074MB.

Hope this helps some!

I recommend removing any/all programs you are willing to, especially the ones you never use. Do a complete uninstall. Then run the windows install clean up (google it to download) just to make sure the program was removed. then go Start-->run msconfig OR just type msconfig in the search and click go (i'm not sure if you're on XP or Vista/7)

Under msconfig dialog box you should see a section that says startup. Remember remove programs you dont use FIRST. Then disable any startup programs you don't use EVERYDAY. Don't go disabling everything though windows needs certain processes to run, and some processes dont really effect anything. But if you're curious you should be able to google any of the startup items and see what it's related to and why you do or don't need it.

GOOD LUCK! Sorry I'm all over the place with this response.