As others mentioned I'd take a close look at the specs of that computer. On a powerful machine Flexi can chew through multi gigabyte files in just a few minutes, a 52 megabyte files should rip in a few seconds. Unless there is something unusual with the artwork like Casey mentioned. I've also seen the once in a rare occasion odd thing that chokes Flexi - usually either some messed up effect or possibly a monster of a vector with a zillion points duplicated many times.
I'd also reccomend (if possible in your situation) running Production Manager on a separate dedicated computer and Flexi on you design computer. It frees your system up very nicely. Our rip computer with Production Manager is pretty bare bones - actually somewhat old but fine for the dedicated RIP. 2.66 Core 2 Quad, 8GB ram, dual 250gb hard drives, Windows 7 x64, and FlexiSign. No fancy video, screensaver, pretty much Windows only stripped to the bare minimums. No other programs run on that machine, no antivirus, firewall disabled, etc. It is NOT used for anything else - Production Manager added to the startup group and it's set to auto logon to our network. It tears through files nicely and just drives the printers and the cutter.