Ajax error

[pm4698]

Hello there,

One freelancer, took care of an e-shop i was building in order to optimize its speed and he did great job on this! He told me that he added some code in web.config and/or .htaccess file


But, some times during the day and for several minutes (for example 5 minutes), when i try to use some modules at front-end like bt-login module or one page check out module or even a pop up plugin, i get this error message in a pop up:
error: Ajax request failed

After several minutes it fixes by itsown. But i don't know what it is and why is happening just in a few times and for a little while

Any ideas?