Anytime I cut a square inside profile, two of the inside corners have a long radius......anyone know what could be causing this?

I looks right in Aspire, but cuts out like this.......see picture below.

Does the tool path look correct in Mach 3?

If it does and you're using CV mode and your accel could be too slow on one axis (but not the other) to keep up with your feed rate, Mach 3 will round the corners as it's trying to pick up speed to change directions while maintaining your feed rate.  If this is indeed what's causing your troubles, you could try the "exact stop on angles greater than" setting and set it to perhaps 89 degrees and see if that fixes it.

I would take a guess at it being backlash..
Hood

I'll check the things you guys mentioned, but the odd thing is it's always on inside profiles.......I can cut a outside profile and it works fine.

It could be what Hood and Peep's posted but also make sure that the radius of the of the tool is smaller or equal to the radius of the corner your trying to cut, else the program may round the corner to suite the cutter.

RICH

I'll check the things you guys mentioned, but the odd thing is it's always on inside profiles.......I can cut a outside profile and it works fine.

When going around an outside corner, CAM software usually uses an arc in the tool path, even with a square corner leading to a gentler acceleration.  What's the accell settings for your X & Y axes?