What steps will reproduce the problem?

1. Engage Gul'dan on Heroic. I didn't see these errors on normal earlier in the week, but I might have had a different version then.

What version of BigWigs are you using?

v36

Do you have an error log of what happened?

http://imgur.com/a/b14I4

Please provide any additional information below. (example: localization of your client if not enUS or enGB)

Thanks for your report.