I am in tears.. almost.
First, my drupal site went so frustrating slow, that I decided to do some debugging. loose some modules, add some modules, messed with .htacces and so on. like everybody has with D7
In the end speed was same as before. Frustrating hours went by.

until I decided to have a look at my beatifull product page, and saw that the prices are not displayed correctly, it looks like al prices are with the wrong product.

to make things worse, using commerce backoffice to look at my products, pages cannot be loaded, displaying error message:

An AJAX HTTP error occurred.
HTTP Result Code: 200
Debugging information follows.
Path: /shop/?q=views/ajax&render=overlay
StatusText: OK
ResponseText: @import url("http://hazmedsdisastermanagementproducts.nl/shop/modules/system/system.b...");

it repeats the last rule with the .css part in it several times (plm 50) with different terms
( I did not enable css compression in the "performance tab under configuration), I did install boost module, but it did not work, probably cause i did not get clean urls to work, so I deleted the module and reset my.htacces)

can someone help me out?