I'd bet that if the OS is windows he's letting Windows "control" the ram usage under Video performance settings.
On your Desk Top at My Computer right click bring up Properties.
Select Advanced Tab
will have this warning at the top of the popup "You must have administrator rights to make most of these changes."
Just under this is the Performance section, left click the "Settings" button.
This brings up the Performance Popup Screen. First Tab is Visual Effects.
Most likely the "Let windows choose..." radio button has a dot in it. This is windows controlling you ram (both video and on board).
Instead select either "Custom" or "Adjust for best performance".
If you choose "Custom" only select the options you really need, usually 4 or 5 is all that is needed like "smooth font edges", "Use common tasks..", "use Visual styles.." and either "use background.." and/or "Show window contents.."
Any thing more and you begin to use more of your ram for windows than for the game.
Next tab on this popup is Advanced.
Select it.
2 choices; Processor scheduling and Memory Usage, Select Programs for both.
Bottom of Popup; Virtual Memory.
Set VM to (if you have at least 2 gigs of rams) 2046 MB use the change button to do this.
If you have more than 2gigs of Ram AND a 64bit OS you can set higher.
If you have more than 2gb of ram AND a 32bit OS then it depends upon the OS.
ex. Win XP Pro 32bit, if you have more than 2gb of Ram the *3GB Switch is a must. The 3GB switch "How To" has been posted in this Forum. Use Search or a manual scan of older Threads.
JosEPh
Ps I have a 64 bit Win XP Pro OS and I do NOT have CTDs and MAFs . I also use 8 gigs of DDR2 1066 Ram (a bit of overkill

) but my vid card is only 512 MB of DDR3 ram a Radeon HD 4650 card (modest price under $80 ).