You say you have updated all drivers including th motherboard chipset drivers..
You do not have an add-in IEEE 1394 controller ...
You have not changed any connections since the port worked before...
What brand of firewire controller does Device Manager show it is?
Operating System Win 7 x64
Computer Type Homebuilt
OS Service Pack 2
DirectX Version 11
CPU Type and Speed i7 3770K
Motherboard Chipset Asus P8Z77-V Pro
System Memory Type 16 GB Kingston
Video Card Type and Speed Nvidia GTX 680 (2)
Computer Monitor LG 27" (3)
Hard Drive Kingston 240 SSD
Optical Drives LG WH12LS30 Blu-
Modem-Router Type Linksys E3000
Network Adapter Intel Gigabit
Anti-virus Software MSE
Computer Skill Level Average Ability
Windows Experience Index 7.7