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 tags
create excerpt
add bits with Amazon reLoaded plugin
schedule post
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
Gaz