network problem

I have a problem with a computer in my company after logging into windows the network connection only stays active for a few minutes then cant be accessed again. I have tried putting in a pci network card thinking the onboard lan was responsible but it still does the same thing I uninstalled the firewall and virus software and any software that was added prior to the problem but have not had any luck any help would be appreciated.

 

This just start or anything change at the PC lately?
Added software?
Added Hardware?
Moved the furniture?
Does it come back if you unplug it & plug it back in?
The few seconds it is on, does it get an IP? Not a duplicate is it?
Try moving ports on the wall and the switch?