Problem with PIC16F87

[mackrackit]

Not knowing how mains are wired where you are at but I will guess that there is a problem in the way they are wired at your place.

I had a similar problem at a customers place. A lot of high frequency "stuff" runs (similar to your smoke machine?). After spending time changing the power supply, adding capacitors etc I found the problem was bad or no earth grounds on most of the equipment. Several places the ground wire was connected to the machine but not to a ground rod creating several antennas going several directions.

I went though and fixed and or added the earth grounds and the problem was solved. The false alarms on their security system even stopped. Not sure about that one, just what I was told.

Might not be the problem, but just from a safety side it would be worth a look.

[The Master]

I dont think the 555 problem is caused by grounding problems. Its on the same PCB using the same ground as everything else. The smoke machine itself is definately earthed correctly and ive had the same problem in a few different buildings. The PIC also resets if i plug something like a soldering iron or big transformer in and the ignition on our gas cooker causes a reset too. These things have affected every PIC circuit ive made so i guess they are normal but im just wondering if the 555 is creating a similar kind of interference thats so small that it only causes a problem when its connected to the same power rails as the PIC.