I recently had a boot failure on my SME 7.5.1 server giving me the 
Grub error 17 message.
The SME rescue failed and I needed to recover files.
Searching in the SME forums I came across a pointer to 
www.chrysocome.net which has some interesting recovery tools.
As the file system on my server is LVM2 I decided to use the beta version of 
http://www.chrysocome.net/virtualvolumesThis allowed me to recover my data.
Be aware that this is a 
Beta version so use at your own risk, (but I was desperate),
Cheers