Error code : 80042802. xxxx.dll apperas to be an unsigned assembly which is disabled from executing as spcifed in workflow.config
When you call assemly from Workflow you may get this error. Microsoft CRM 3.0 workflow does not support unsigned assembly.You should specifically determine to Workflow engine to use unsigned assembly. To do this just add allowunsignedassemblies="true" into Workflow.config.xml which is probably in "C:\Program Files\Microsoft CRM\Server\bin\assembly" directory. result will be ;