Vegas 9c still with rendering issues

Hello,

I am still getting "not enough memory" errors when rendering MPEG files. Settings are for M2T 1440x1080 60i which is my native resolution. Cannot render to the same file type without often having the memory error. I have seen that numerous other have the same issue. I can render to 720p with no problem, as well as mpeg2 no issues. I have been using the same protocol for years with Vegas 7, 8 and 9 and have only recently had these issues with memory errors. Does the same thing on another one of my computers as well. Both are dual and quad core machines with 4gig of ram, XP Pro machines and have been using them for projects for years. The only change is Vegas....any thought? And thanks!!