Cannot log into zencart admin, get a crash error

Hello Everyone! I cannot seem to find this issue anywhere else, but forgive me if I missed something.

Our sites runs an older version of ZenCart (v 1.3.7) which is going to be updated, but for one of our sites it is a rather large job that cannot be immediately done. We have had a few hack attempts the last couple weeks and it seems there are a lot of "holes" in our site.

My initial problem beginning last week is that customers are unable to create an account, when they hit 'submit' this error code shows up:
"1062 Duplicate entry '0' for key 4
in:
[INSERT INTO zen_customers (customers_firstname, customers_lastname, customers_email_address, customers_nick, customers_telephone, customers_fax, customers_newsletter, customers_email_format, customers_default_address_id, customers_password, customers_authorization) VALUES (...(personal customer info)...)"

However now, I am unable to do the recommendation I found because our Zencart admin has crashed! This is the error I get when clicking submit at the login page for the admin area:
"144 Table './chw/zen_admin_activity_log' is marked as crashed and last (automatic?) repair failed
in:
[insert into zen_admin_activity_log (access_date, admin_id, page_accessed, page_parameters, ip_address) values (now(), '0', 'login.php ', '', '70.176.66.20')]
If you were entering information, press the BACK button in your browser and re-check the information you had entered to be sure you left no blank fields."

Furthermore, in phpMyAdmin the Zen_admin_activity_log folder brings back a similar error:
" MySQL said:
#144 - Table './chw/zen_admin_activity_log' is marked as crashed and last (automatic?) repair failed

I am in way over my head here and have no idea how to rectify this situation. I spoke with my hosting company and they informed me it is a zencart error and not anything they can do. If anyone has any idea how to maybe fix this, I'm all ears! I tried contacting the hired help we have for this, but alas no reply :(

Thanks,
Ryan H.
CornerHardware.com

Have you tried manually repairing the database in CPanel ? Should be an option under 'mySQL databases'.

Thanks Steve, Our hosting company doesn't use Cpanel...I spoke with a rep there and they said they "fixed" the problem and should be no need for repair. I'll believe it when I see it!!! In the meantime I asked them to tell me how to repair a database if they don't use Cpanel for future reference.