Hi Janis,
This could be related to an update that was made or perhaps something else. Here is the meat of the error message above: Table alias a_a6c5656928764aa0b23a0994a7902ca7 is not unique amongst all top-level table and join aliases. Something with the FetchXML has been corrupted and needs to be corrected. There does not appear to be a simple, straight forward way to correct this issue. Here are a few links to possible solutions depending on how comfortable you are making the updates:
blog.salesmetrix.com/.../corruption-of-views-dynamics-crm-2011-online-dec-2012-service-release
Good Luck!