I'm getting a similar error - WP 2.6.3 on PHP 4
Begin a new post - create title and start typing content.
FIRST auto-save works (usually around 3rd paragraph)
continue typing for an hour or two, insert graphics etc.
add bits with Amazon reLoaded plugin
all the while the auto-save is dimming the Save and Publish buttons to say it's auto-saving periodically.
Then hit either Save or Publish (doesn't matter which) and I get a white screen with similar error to first post above - refresh doesn't clear it, waiting 20 minutes and refreshing doesn't clear it.
Before refreshing, hitting back button gives empty new post page and all work after first auto-save is lost.
Only the post as at the FIRST auto-save has been saved - everything created after that has disappeared, i.e. only the title and first few paragraphs are saved.
No errors show during the subsequent auto-save dimming of the save and publish buttons.
There are no incremental save records after that first auto-save.
This has been happening consistently for me since upgrading to 2.6.3 from 2.6.2.
In the last 5 days it has lost over twelve hours of post creation for me, and is a MAJOR BUG from where I'm sitting - every time it happens I have to live-chat with my hosts and get them to unlock the SQL server so I can get back into WP admin.
(public side is generally not affected for some reason - though it was once, on Thursday last, the second error after this all started).
I have multiple sites on multiple hosts, and so far it's just one site on a UK host that's causing this - it's the only one still running PHP 4 All the others are on PHP 5 and not suffering this.
Does anyone have any clue what is causing this?
By the way, manually saving in steps of under 2-3 minutes does not get hit by this - could it be some form of server connection time-out caused by apparent inactivity (i.e. not manually connecting to the server for X minutes? And if so, is it WP or the server causing this?)
Really need this sorted, and fast