[TYPO3] Serious Problem Upgrading from 3.8

[Mark Pi]

Getting the following error in the page tree column of the backend:

> Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/silk/public_html/typo3_src/t3lib/class.t3lib_db.php on line 789
> 
> Warning: mysql_free_result(): supplied argument is not a valid MySQL result resource in /home/silk/public_html/typo3_src/t3lib/class.t3lib_db.php on line 826
> 
> Warning: Cannot modify header information - headers already sent by (output started at /home/silk/public_html/typo3_src/t3lib/class.t3lib_db.php:789) in /home/silk/public_html/typo3_src/typo3/template.php on line 613

The page tree doesn't load (and neither does the template).

Frontend pages fail to load with:

> Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in /home/silk/public_html/typo3_src/t3lib/class.t3lib_db.php on line 801
> 
> Warning: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in /home/silk/public_html/typo3_src/t3lib/class.t3lib_db.php on line 801
> 
> Warning: mysql_free_result(): supplied argument is not a valid MySQL result resource in /home/silk/public_html/typo3_src/t3lib/class.t3lib_db.php on line 826
> Error!
> 
> No pages are found on the rootlevel!


I followed most of the advice in the previous posts relating to database 
errors, but none of the fixes work (checking, rebuilding DB, etc.)

I re-imported the database several times, checked it by eye for 
mistakes, and tried different ways of importing the database -- all with 
the same result.

All of the plugins were updated, then switched off-then-on to see if 
that made any effect -- none.

Running 4.0.2 with MySQL 4.1.

Any ideas?