This is a recurring problem and occurs a few times a week.

I have an external hard drive which is hfs+. Every couple of weeks, for no obviuous reason, when I mount it by pluggin it in to my Ubuntu 11.10, it is read only and I can't copy any files into it.

I gksudo nautlius and change the ownership and it magically works in some time. But returns to the read only state soon in a few hours-days without any rhyme or reason.

Right now my fstab doesn't have any entry for my hard drive. What gives? What in the world is going on with Linux/HFS+? This is frustrating. I can't reformat my hard drive because I have almost a terrabyte of data in it and no receptacle to hold it while I reformat it.