Summary:

Issue with report setting to select only the reports relative to the previous weeks in the search criteria on 7.0 and 7.1 installs.

Symptoms:

1. This is for reports where the search criteria uses some form of date field.
2. For this example the 'opportunity: close by' date field was used as a search criteria in a report based on opportunity.
3. Select the "relative to: previous week" option on the second page in the report setup. 
4. Once the report is run if a example opportunity had a close by date in the previous week (6-12/01/2014) the report will show the reports from that week in the previous year instead. (6-12/01/2013)

Workaround / Resolution:

Use the dates between selection option instead of the previous week selection and just select the first and last day of the week.

More info:

This is not an issue in version 7.2.