Windows 7: Memory Leak. Backup to Network Drive runs out of RAM.

I have been using Win 7 Professional, Backup and Restore sucessfully for almost a year where I have been backing up my computer (250Gbyte Sys Image and 150Gbyte User Folder) to a network dual RAID 2TB each hardrives.

A few months ago, these backups failed to complete sucessfully, causing the computer to lock up. At first, I thought it was becuase I left the computer running for too many days but it seemed to lock up every Sun morning which is when I discovered that it coincided with my scheduled backup time.

What happens is during backup, the RAM memory slowly increases until it gets into the mid 90%, the computer locks up and displays an error message, not enough memory.

I have reduced my backup size from 150Gbyte to 50GByte and I still get the same result
I have completely started over with a new backup setup, selecting the network drive etc. No luck there.
There is over 700GByte of free space on these backup drives.

My Computer is a DELL XPS400 with Win 7 Professional, that has regular OS auto updates.

I also have a DELL Vostro with Win 7 home premium and it continues to backup successfully to this network drive?

Please help as I have tried chkdsk /r and Clean Disk etc

I found the problem and it also explained other issues I had on the computer where I could not even backup my iphone.
McAfee AntiVirus Software
All my issues dissapeared once I removed this software. The computer now operates much much faster, no memory leak. RAM always around 40%.

thks to those forum users who pointed me in this direction.