Does your model run on other computers with the same version of music as yours?
If your model runs on another computer then compare your music configuration to the other computer. Check where your temp files are being written to (Setting>>Preferences) and ensure that you have 'write' permissions for that folder.
If necessary, send a copy of your music model to firstname.lastname@example.org and a member of the support team can test run your model for you.
Does your model have unusual parameters (large number of nodes, long time series [30+ years], user-defined nodes), or something non-standard like a closed system being simulated?
Large models may take an unusually long amount of time to finish running, depending on the amount of data that is being processed. For example, if you run the model for one year of daily data, you will have 365 predicted concentrations. However, if you use 6-minute data, you will have 86400. Longer data sets means less variability between separate runs, but also increase processing time.
Does the model run if an alternate meteorological template is used?
Create a new meteorological template, open for a new model and, then copy & paste the nodes in, then run with new template.
Does the model run if specific components or nodes are removed?
Divide the nodes into multiple pieces and copy into a new model template, and then test. If any of the sections fail to run, examine the parameters of each node for unusual configuration. You should test running this new section without individual nodes to see if there is a common denominator.
Are you running the most recent version of music?
music version 6.0 has been released and includes a number of improvements, including fixes to common model issues and bugs.