funny memory problems Mathcad 15

After removing some variables in the programm, Mathcad still behaves like a donkey not willing to surpass 5000 iterations creating new vectors <1000 entries long. The latest error message  is about "accessing protected memory" indicating "corrupt memory". Does this refer to physical memory?

My configuration is 3 GB used memory with 32 bit W7.

Is there an easy way to get back som flexibility, using larger matrizes?

thanks