Denford Software & Machines

i'm new to CNC and i have a new problem:
i am getting "machine error: cannot connect to the machine" for the microlathe and computer that i have been using successfully until now..
one possible problem: i am using a powerstrip switch as an emergency stop (cuts all power to the machine) since the emergency stop button is not working. could i have messed up the machine by doing this?

Is it RS232 or USB connection to the machine ?
Is the machine and PC connected to the same power strip ?
Either way it could be an earthing fault which has damaged the port on the machine or the PC - not directly because you are using a power strip to turn off, that should be fine, but the power strip may be plugged into a different earth, or it's earth is missing ?

connection is rs232
the machine is alone on the power strip. the computer was plugged into a wall outlet beside the power strip. this is a new school building so i can't imagine that the earths are different on two outlets beside each other. i checked the earth on the power strip and it is good. just to try, i've switched the powerstrip to the same outlet as the computer and the problem persists. i don't have the computer on powerstrip because i don't want to shut it down improperly when i use the powerstrip as an emergency stop.

You need to verify the RS232 and cable is working:
This post is a good start:
viewtopic.php?t=544

i took a summer vacation and i'm back on the job, but still can't get this microturn to connect. i switched the fuse on the board. this did not work. i built a test cable. when i unplugged the cable from the board i noticed a lot of corrosion on the pins. tried the test cable anyway and it didn't work. I cleaned the pins and plug with contact cleaner, then tried the original and test cable. no luck. i installed vrtuning on another computer. that didn't work. then i did the same to a newer computer (windows 7 instead of xp) and still had no luck. any other suggestions?