Turnaround time with work hours - IT Help Desk

Although there are several posts regarding similaar topics, I have not been successful. I am now using the following formula:

=MIN("7:00",MAX("0:00","18:00"+INT(C2)-C2))*NETWORKDAYS(C2,C2)+MIN("7:00",MAX(D2-"7:00"-INT(D2)))*NETWORKDAYS(D2,D2)+"7:00"*(MAX(0,NETWORKDAYS(C2,D2)-2)-(INT(INT(C2)/INT(D2))))

A2 = Start time of workday
B2 = End time of workday
C2 = Ticket submitted date & time
D2 = Date & time ticket was initially triaged.

Attached spreadsheet showing E3 with a triage metric of 3 hours and it should be 2 hours (workday started at 7:00 but ticket was submitted at 8:00 and responded to at 10:00.

Any help would be greatly appreciated.
Thank you!

Yes, weekdays only. Thank you, I'll give it a shot.

Thank you, Thank you, Thank you! This works and I may actually sleep now. Much appreciated

I've run into a problem. If the submitted time 4/22/13 22:05 and the response was 4/23/13 7:59 A.M., it returns "############" for the turnaround time, when it should be 0:59. Similarly if the submitted time is 4/7/13 3:10 A.M. and the response was 4/8/13, 9:24 AM, the turnaround time returns "##########".

I don't know if the problem is with the formatting of my cells or what.

May I ask for help again please?

This formula works beautifully; thank you! I'm having a hard time understanding the different parts. Would be so kind to break it down for me so I can understand what each piece of the formula is accomplishing/stating so I can copy it for another similar date requirement I need?

Thanks so much!
Eileen