If you open LibreOffice (no application) and click on Help, LibreOffice Credits or in Help, License Information, Show License, closing those documents will also close LibreOffice.
This is not a big problem. Just unexpected and annoying :)
Was found to occur in LO 3.3.x, 3.4.x and 3.5.x under Windows XP Pro x86 SP3
I Also have the problem.
When a document is open then it doesn't close the LibreOffice. So it seems that it recignises that it is the only open document and then will close LibreOffice.
*** This bug has been marked as a duplicate of bug 30920 ***