I can't open your Creo 5 model (I'm on Creo 4), but maybe someone else can take a look.
Can you share a screenshot of your folded model in a 3D orientation (with the dimensions shown)?
I spent over 2 hours on your model and finally came up with a solution. Your issues are due to model accuracy. Creo doesn't like when you have extremely small surfaces in relation to the overall size of the part, and I think the rounds on the bottom of the pan were making extremely small surfaces which became a problem when the size of the part was increasing in width.
What I ultimately did to solve this was right click on PRT_CSYS_DEF, select "Insert Here", go to File > Prepare > Model Properties > Accuracy, change from "Relative" to "Absolute", enter the smallest value I could (0.0015), regenerate, and exit Insert mode. Once I did that I was able to successfully create a drain pan that is 100 x 100 with no regeneration errors, whereas with your original model I couldn't get one larger than 8 x 12 or so.
Now at this point it may be tempting for you to change the accuracy of your start parts to Absolute 0.0015 and never have to worry about this again, but I advise against that because I think that lowering the accuracy number can increase regeneration time. (I could be wrong though.) So, I only change model accuracy when absolutely needed, which is usually when I have an unexplainable regeneration error like yours.
Hope this helps,