Exit from descent mode

Hello!First I would like to thank the wonderful PMDG devs for the excellent MD-11. I have been a huge Tri-Jet fan and this is excellent! I have had an issue on the last 2 flights while learning the sim and can't figure out how to fix the issue.I accidentally dialed in an altitude lower than cruise and the aircraft went into descent mode on one flight, the other I pulled the alt hold knob on the MCP and the FMS locked me out of the CRZ altitudes displaying --- / --- instead of [ ] / ---. Every time I attempted to enter an altitude I was given the NOT ALLOWED statement. The aircraft began thrust reductions to 290 and was still displaying the cruise altitudes in the F-PLAN page but would not enter PROF mode again.I tried opening the flight plan in the SEC F-PLAN but I could not activate it. I then copied the active which allowed me to enter an altitude. When I pressed activate FSX crashed as an apphang.Is there a method of exiting descent mode when entered accidentally?Thank you in advance for all of the help.Regards,Mike