I don't think this error is directly related to Win32::TieRegistry. The are report of this same error occuring when using Win32::AdminMisc and Win32::NetAdmin::CreateUser

Common elements seem to be apis that are communicating across the LAN, and an NT machine talking to a "K machine or vice versa.

The error is indicating that a previous call to some (network) IO was started asynchronously, and it hasn't yet completed, or it hasn't been reset prior to another attempt being made to perform further IO.

I think that you may be able to work around the problem by inserting a delay prior to calling which ever call is resulting in the error. I'd start with using 10 seconds, and if that is successful, slowly trim until the problem returns. I would use Win32::Sleep() in preference to perl's sleep as it allows millsecond increments, and may also relinguish more timeslice to the system and allow whatever process needs to complete, to complete more quickly. It is available by default on AS builds of perl, there is no need to load any extra modules to gain access to it.

The fact that the error is occuring from totally separate API's, and also I saw some evidence that it can be related to connections made from NT to 2K machines when perl is not involved, which suggests that this may well be a system level bug or failure rather than a perl or module problem per se.

Please come back and report your findings if you try this. Thanks.