my sql wont download backup, el system log problems

I have a problem with my elgg my sql data base, when i try to back it up i cant it wont let me download a copy, i have contacted my host and  there blaming it on the elgg data base,

There saying the el_system_log db is the problem, and stoping us be able to take a copy.

The whole db is 154mb but this el_system_log is 142mb, so am scared to clear it without backing up,

Can i clear the el_system_log records without harming my site? its just a log right?  i of course would normally back up before doing anything with the db but i don't seem to have that luxury,

But el_system_log is just a log right? so its not gunna do any harm to delete the records?

 I would be realy realy greatful for any advice,