I think I pretty much proved to myself anyway that SP12 doesn't like my plist, and the three backups didn't change that. i didn't bother going back to DVDs for older or different backups.
I tended to make a copy, duplicate, then rename some of those copies so I would know when.
And, because I was NEVER EVER having ANY problem in the last 6-9 months (but had had problems in the past with odd behavior) I would on a monthly basis or something duplicate the plist.
I thought an old problem with crashes when closing windows was related to couple different things and that was when I tried to narrow down the cuplprit(s).
- things like: Microsoft Mouse driver (fine), Bookmarks created by Bookit, etc. Went on for many months and more than a few feedback's of Activity Monitor output from Sample even.
And the last thing I wanted to do was redo all the preferences that go into OmniWeb5 plist.
Writing to that file so often, when closing a tab even, seems asking for trouble.
MSIE use to get into trouble with the Internet Preferences file becoming corrupt.
OmniWeb is my most used app probably, and the only one that could be said to have trouble crashing. (It got to the point I removed OmniCrashguard itself - seemed more like the olde Norton Crash extension that caused more than it helped).
Still doesn't say if problem was the tip someone at OmniGroup gave me for using the Terminal to write changes to the plist to change a few options for which there wasn't a preference to set via GUI - but probably could have been changed just as easily in Property List Editor.
Bottom line: Have a new plist for 5.5, and maybe a new site pref file as well but over in ~/Library/Application Support/OmniWeb 5