I encounter a little bug in the 7.1 version of eagle.... ant this bug can easily reproduced :
-> create schematic. and a new page.
-> edit the description of the page (right-click+ Description, in the sheet tool bar.) and give a description with the ':' character (example "SUPPLY: part 1").
-> then display a other page.
-> if you wish to display the page with a ':' name, 2 options:
* You click on the thumbnail of the corresponding sheet of the 'sheet' tool bar: that option work fine.
Eagle is a nice boy, before opening this new empty document, it will ask to save the previous document if it was not saved, and if the board corresponding to the previous document was open, It will warn us that no forward-backannotation will be performed... really nice, but I think that I didn't ask for a new empty document....