Please check if there are cyrillic characters in permalink field on “Edit Product Tab Type” page. You can find this page in “Product tabs” menu on the wp-admin area, and edit your defined tab types.
If you find cyrillic characters in the permalink field, please change it to normal ascii characters.
Unfortunately, if you set tab content previously to your products, you have to set it one more time in case of these tab types.
Please let us know if this does not solve the problem.