Fought through a problem yesterday only to discover it was caused by a SW setting, so I thought I would share that info here.
User had locked an assy and all its files in our PDM system, so he then had write rights (I love using those 2 words together...). Then he opened the assy in SW and found that while the assy was just fine, all of the parts in it were read-only, even though he had locked them. This was confirmed by looking at the read-only bit on the files - no bits set to read-only. We went through all the usual stuff and finally found a SW setting that was causing it. System Options/External References/Open referenced documents with read-only access. Somehow that one got turned on and was doing just what it says it will do. How it got turned on, we don't know - the user said he didn't do it, and I believe him. I also checked and it's not turned on in my master settings file. Strange indeed!
Maybe this will save someone else some time & grief.
WT