A nice theory bites the dust

Don't be too quick to write it off - let's just say that the jury is still out (and probably will be for quite some time).
One day something will crop up that will lead to that "aaaaah" moment.

I can't see anything in my environment variables that could be causing different behaviour. Here's the full list on my XP laptop:

ALLUSERSPROFILE=C:\Documents and Settings\All Users
APPDATA=C:\Documents and Settings\Owner\Application Data
CLIENTNAME=Console
CommonProgramFiles=C:\Program Files\Common Files
COMPUTERNAME=ACER-RT1U8HQ3DR
ComSpec=C:\WINDOWS\system32\cmd.exe
FP_NO_HOST_CHECK=NO
FTP_PASSIVE=1
HOMEDRIVE=C:
HOMEPATH=\Documents and Settings\Owner
LOGONSERVER=\\ACER-RT1U8HQ3DR
NUMBER_OF_PROCESSORS=1
OS=Windows_NT
Path=C:\perl510_M\5.10.0\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS
+\System32\Wbem
PATHEXT=.COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH
PROCESSOR_ARCHITECTURE=x86
PROCESSOR_IDENTIFIER=x86 Family 15 Model 2 Stepping 9, GenuineIntel
PROCESSOR_LEVEL=15
PROCESSOR_REVISION=0209
ProgramFiles=C:\Program Files
PROMPT=$P$G
SESSIONNAME=Console
SystemDrive=C:
SystemRoot=C:\WINDOWS
TEMP=C:\DOCUME~1\Owner\LOCALS~1\Temp
TERM=dumb
TMP=C:\DOCUME~1\Owner\LOCALS~1\Temp
USERDOMAIN=ACER-RT1U8HQ3DR
USERNAME=Owner
USERPROFILE=C:\Documents and Settings\Owner
VSCOMNTOOLS="C:\vsnet\Common7\Tools\"
windir=C:\WINDOWS
[download]

Cheers,
Rob