Can't shrink Log file - "An invalid Floating point operation occurred. (Microsoft SQL Server, Error: 3623)"
You should update your question with the full @@version of your server.

You mentioned only that you use SQL Server 2008 R2, if you are only on SP2 this hotfix is for you:  Cumulative update package 8 for SQL Server 2008 R2 Service Pack 2

Among the issues it fixes, there is yours:



But I recommend you to patch your server to SP3.