Monks, enlightenment just dawned -- and what a relief it is with 5 mins to go before the weekend! The file assocation for .pl in fact said:

"C:\Perl\bin\perl.exe" "%1"

so I just added the %* at the end as per the suggestions and now all my scripts work fine again! Many thanks to all who took the time to answer; ++votes from me to y'all.

Cheers, mooseboy