IIS log failed to write entry (IIS6)

Hi,

I found this event:

Event Type:    Warning
Event Source:    Active Server Pages
Event Category:    None
Event ID:    9
Date:        22/11/2012
Time:        6.01.11
User:        N/A
Computer:    ComputerName
Description:
Warning: IIS log failed to write entry, File /LM/W3SVC/1040253177/Root/global.asa Line 537 Variable is undefined: 'ConnUtenti'. .

Please,

let me say where can I find the IIS logs, the line 537 (which file? Which website?) and what kind of variable is "ConnUtenti"...

Thanks so much!

Alex