When opening a Report i get an error that says the search key was not found, after clicking ok it opens the Report normally, but i could do without the error.
That message usually indicates corruption. There's a number of ways to get a corrupt database, some of thethe most common being having an unsplit database with multiple users or using an Access database over a wireless or otherwise unstable network.
What I would do is dig through the tables that relate to that report and see if you can find a record with damaged data. It might look like the data is a bunch of Chinese characters, or a bunch of ########### or the like. Remove that record and then create a new database and import all the components from the damaged database into the new one.
If you can then compact you should be ok but you may want to look into how the data became corrupt.
Many times, if there is a corrupt record, you may not be able to delete it until you run Compact and Repair. If you do, save a copt as a backup first. And once done you will find the record by looking in the PK field a where there is nothing there.