What file are you attempting to load into the database? How are you trying to load it (a PHP script, phpMyAdmin, something else)? Can you copy the first few lines here so we can see if it has been corrupted?

I kind of hesitate to press the "proceed with database installation" button on your site...

In a .sql file, a line starting with '#' should be ignored as a comment. If that line 1 is really the correct line, I can't see what the problem is from here.

One thing you might check is whether the database itself has been created already, and if so, have any tables already been created? Go into cPanel > MySQL Databases > phpMyAdmin and see what's there for osCommerce-related databases. The database name should be "<your account>_osc1" or something similar. Ditto for user(s) it created. Maybe you missed a step to create the database in the first place, or the user-creation failed, or the script failed in some way. If any of those happened, trying to do further setup or loading of the database will fail, although I would think you'd get a clearer error message.

Next, what is in this oscommerce.sql file that it's trying to load? Do you see commands like "CREATE TABLE address_book (
    field_name  type(size) other_info,
    field_name...
) TYPE=xxxxx;"

and perhaps
"INSERT INTO address_book (fieldname, fieldname,...) VALUES ('a', 'b',...);" ?

For anything beyond that, I'll need access to your account to go exploring. It's probably something minor that I won't have to charge for. I don't think LP's support will help, unless you can show it's a system problem. Let me know...