the only big difference would be that sles 11 sp1 used a 2.6.x kernel whereas sles 11 sp2 uses a 3.x kernel

i'd think that the newer kernel could be the culprit

and looking at a doc from a quick googling doesnt mention any sles 11 sp2 support, as well as several other people with issues with kernel 3 linux guests (not just suse)