Downgraded from MySQL 5.0.20 to 4.1.11 [Errors- ERROR 1033 (HY000): Incorrect information in file]

[bob ly]

I had to downgrade MySQL from 5.0.20 to 4.1.11 ( The version I was previously running).
I uninstalled the rpm packages for MySQL 5.0.20 and then installed 4.1.11. I was able to successfully downgrade and the server started.
While installing i got some errors but I was able to instal it. There errors were ERROR: 1033 Incorrect information in file: './mysql/help_keyword.frm'
Most of them were mysql DB tables. But some of the tables in my database are corrupted and I get an error message

ERROR 1033 (HY000): Incorrect information in file:

infact I tried mysqlcheck --check-only-changed --all-databases --use-frm -repair
and also mysql_fix_privilege_tables. But still no luck.

Please let me know how do I restore back the tables.

Thanks in advance