You have described a HDMI Handshake Problem.
One common problem people experience with HDMI is handshake failure. Sometimes, this is because the HDTV is an older, DVI-based model without HDCP support. But in other cases, there's an easy fix -- unplug your components and power cycle your system. This may reset the authentication cycle and restore your connection.
To do this on a laptop you will need to remove the battery and the mains and hold the power button for 10 secs - then power on without the battery in just off the mains. We take it the tv has already been dissapated when you took it to panasonic shop.
If this doesnt resolve have you tried a longer hdmi cable ?
A Hdmi switch box ? that may be next
something like http://www.amazon.co.uk/Port-HDMI-1080P-Switch-Splitter/dp/B004H1IKKK/ref=sr_1_13?s=electronics&ie=UTF8&qid=1331129460&sr=1-13
ask your tv place to test that
most of the problems you describe are fixed via Hdmi switch box - i dont know why it is suddenly misbehaving.
1) the HDMI cables are certified category 2 cables (cat 2 is sometimes called "high speed").
2) The total length of the cabling does not exceed 10m.
3) Important ** check your driver for your video is this one from the driver site http://support.ts.fujitsu.com/Download/Index.asp?lng=com&Level1=&LNID=1
Intel® HD Graphics 126.96.36.1995
to check goto start search programs and files. type DEV - click device manager - then down to display adapters double click the listed intel - click the driver tab and match it with the one i put above. If its different then windows updates likely altered the driver (its annoying like that)
Could it be windows 7 disables the TV and you need to re-enable. Other post found of same problem with Panasonics/wXP