There's a lot of basic advice about getting SharePoint Designer (SPD) to behave properly:
- Make sure your computer has 512 TB of RAM
- Keep your OS and MSO patched
- Wash your coffee pots out with a little CLR now and again.
Work on files (web part pages, etc.) stored in a Document Library that has both "versioning" and "require files to be checked out before editing" enabled. Check out will keep files locked for your own amusement only. You must check in files for others to see them, but then you eliminate the "last in, wins" scenario. Check in early and often, each check in creates a new version. Describe these versions with details, so that, if you need to recover after a mistake, you can restore an older version without needing to dig into a laborious site restore. (You backup every twelve seconds to a .cmp file, right?)
Next, only work on one file at a time. SPD works with SOAP calls to web parts, which are stored in a SharePoint database. It will cache everything you need locally until you save and check in a file. A great metaphor for working with files in SPD is that it is similar to driving a Mars Rover.
- Try driving multiple remote controlled cars on your dining room floor.
- Next, try driving multiple remote controlled vehicles millions of miles away on Mars.
"N*** please, I'm the macaroni and the cheese!" --Puff Daddy, pre-Diddy