Dear all i have a PABX Siemens 1120 model installed on different locations ,5 locations i have an issue that operator console (Profiset 3030) keys blink and console hangs, other system works fine only hybrid console have thisissue if we just remove line cord from profiset and plgin again it works fine for the next 10 to 15 minutes.(we have replaced every thing like power supply,profiset,internal wiring,line cord, brought system on default but still we are unable to resolve this issue).

Any idea