A while back, the following occurred. The PC is a Dell Inpsirion, running Windows 7. The browser was IE6. The network router was Linksys though the PC was wired to it. The router was secured.
Prior to the curious occurance, the browser history was reviewed. It contained numerous entries for Craigslist. During a browsing session a day after the history was reviewed the history dropdown would expand and the screen in this space showed jagged dancing lines. Then the history would return to it's normal, collapsed state. This process occurred many times.
The next day, the browser history was again reviewed. This time, there were no Craigslist entries.
What is the likelihood that this was random?
Assuming a black hat actor, what skills would be required to delete specific browser history, from a remote location?
What, if any, security information would the black hat need, assuming assistance from inside the network?