Thanks to PMDG support

I just discovered that my DVD/R/RW was faulty ,when it was connected it would cause an "chirping ticking sound from the motherboard audio",.Everytime i tried to do a long flight i would get the following problems "vnav speed disconnects/speed fluctuations/max alt messages,all of which made no sence.It's now disconnected & i have completed three flights without any problems at all, "egll to kbos/kbos to egll/egcc kmco.Hardware caused the "pauses"that paul from pmdg mentioned which inturn would cause the above mentioned problems.I would just like to thanks Paul from pmdg for all hes assistance & if this information helps anyone else ,objective achieved cheers Phill