Major issues with the Solaris

The vehicle is a 96 Olds Achieva bought in 02 with 16,000 miles.  I had the solaris installed in this car for over 2 years with no issues.  Then over this past winter I started having issue with the car not starting manually or remotely.  The car would crank but not turnover.  This only happened on extremely freezing mornings after a long sit. I suspected the passlock I system but no codes were given nor was there a security light.  Then as spring set in,  the car shut off while driving 2 times.  I had the alarm sent out for repair.  Once it was reinstalled a new harness was installed along with a new problem.  The theft light would stay on while manually or remote starting.  Then it progressed to the theft light blinking if manually started then shutdown.  Once the key was inserted and 15 minutes passed the system had reset all was well.  But if the car was remotely started, all was good.  Last week, the car after being parked sounded the siren very very muffled.  There was no response from the security system, ie transmitter or led.  I removed the solaris as it is not reliable what so ever.  Get this, now without the solaris or the 555l the car starts manually without the theft light what so ever?  I'm thinking the 555l was faulty.  Anyone have any issues like this?

Well as far as the in car grounds, they were solid.  The wiring harness was new, as far as the connection internally I never checked.  I am done with the solaris.  I am not risking my life with this piece of crap any longer.  The thing I hate is if the internal relay goes as it did in my case before, you lose ignition.  This happened while on the parkway, not fun.  Then after a short while you can hear the relay click opening back up.  Not a great design aspect for safety.  Thanks for the post