Can't Delete Encrypted Content: Microsoft.ReportingServices.WmiProvider.WMIProviderException: Value cannot be null.

I'm having servere issues with our SSRS. We decided today to change our Admin password over the weekend, this has have the effect of locking me out of our SSRS. Unfortunately we don't have a backup of the Encryption keys either.....

So i'm resigned to deleting all encrypted content. however that isn't working either, i get the following message whatever i try to do.

Microsoft.ReportingServices.WmiProvider.WMIProviderException: Value cannot be null.
Parameter name: key
   at Microsoft.ReportingServices.WmiProvider.RSWmiAdmin.ThrowOnError(ManagementBaseObject mo)
   at Microsoft.ReportingServices.WmiProvider.RSWmiAdmin.DeleteEncryptedInformation()
   at ReportServicesConfigUI.WMIProvider.RSReportServerAdmin.DeleteEncryptedInformation()

I have tried the fixes in the following thread, none of these have worked. I have also deleted the key directly from the ReportServer database following this thread that didn't work either. I really don't want to create a new ReportServer instance, however i fear i'm heading that way.

Anyone have anything else i could try?

Many Thanks

Scotty.