Something I found out recently might help out if you experience a problem eliminating a trouble 7 (wireless problem). It seems, if you have a wireless receiver and at least one wireless point of entry (door or motion) on a DSS 1555 panel, after some time, you may experience a trouble 7, which doesn't respond to changing the battery in the wireless device, defaulting and reprogramming the wireless receiver, or even changing out the wireless component itself. Bottom line, there seems to be some sort of glitch in the firmware somewhere, whereby the panel keeps cycling, looking for a wireless keyfob (even if none is present on the system). If none is actually programmed in the system, after a long length of time, this trouble may permanently "burn in" to the panel itself, and cannot be cleared without changing out the panel for a new one.
It seems the solution is to program in some number other than 000000 in section 41 of the programming in section 804 of the wireless receiver.
I have no idea why this happens, but this is the second occurrence of this problem that I have experienced.
Hope this helps someone else