Your problem is becoming more and more common nowadays. You obviously
have unwanted software running in the background without you knowing
it. From your descriptions, "It flickers black constantly as if
something is interrupting the connection" and "Equally annoying, after
a period of waiting a lot of ie windows seem to default to a useless
website called Perfectnav.com and this really winds me up", something
is tapping into the Internet in the background. You have spyware
and/or adware in your system.
What is spyware?
"A technology that assists in gathering information about a person or
organization without their knowledge. On the Internet, "spyware is
programming that is put in someone's computer to secretly gather
information about the user and relay it to advertisers or other
interested parties." As such, spyware is cause for public concern
about privacy on the Internet."
What is adware?
"while not necessarily malware, adware is considered to go beyond the
reasonable advertising that one might expect from freeware or
shareware. Typically a separate program that is installed at the same
time as a shareware or similar program, adware will usually continue
to generate advertising even when the user is not running the
originally desired program. See also cookies, spyware, and web bugs."
Perfectnav is an adware that comes with Kazaa Media Desktop. You can
remove it by following the instruction in the link below. Simply press
the "Shift" key before clicking on the link so it will open a new
window or right-click on the link and choose "Open in New Window" for
PerfectNav Description and Removal
To prevent this from happening again, please follow the instructions
described in this link:
How To Clear a Hijack
To make it easy for you and to remove other spy or adware programs,
download and install following programs but don't forget to update
them first before running them one after the other:
Spybot - Search & Destroy 1.2
Application to scan for spyware, adware, hijackers and other malicious software.
To update Spybot, click on Search for updates.
To update Ad-Aware, click on the globe icon with a magnifying glass
called Open WebUpdate.
Make sure to keep these programs updated and run them once or twice a
week. Also, make sure to have an antivirus program for further
Search for spware/adware definitions via Google Web Search
I hope this helps you. Should you have any comments/questions, please
feel free to post your clarification before rating this and I'll
attend to you as soon as possible. Thanks for asking.