>>Did you trying to reference it with the full name (master.dbo.sp_MSForEachTable)? Just speculating, not sure it would work.
>>
>>Though it's strange.
>
>It started to work again as soon as I put it case sensitive. I succeeded to make it work as is without having the same casing. Today, this is now a requirement. Have you ever seen a think like that?

Yes, if you set the collation to be the case sensitive when you installed your SQL Server. It also could be set for each database.