Upgrade causes Apps to disappear

Hi,

We've upgraded the Zen Management agents from version 4sp1a to version 7 on
some workstations at 2 different sites. The workstations have XPsp2 and NW
client 4.9sp2.

We used a NAL app associated with an MST file to do this. After the
upgrade, all NAL icons are missing, at both sites. Can anyone help ???

Thanks Muchly
Dennis