Variable plasma picture quality

I've got my Panasonic plasma hooked up to digital cable. A couple months ago we had a lightening storm and the next day I noticed a grainy quality and lack of sharpness to the HD picture I hadn't noticed before. It seemed to correct itself after a couple days.

Then yesterday I noticed the same thing again, but this time no storm beforehand. My assumption is the cable signal is compromised in some way rather than the TV (at least I hope that's the case), but wondering if anyone else has seen this, what may have caused it, and what you've done about it if anything. I don't have another hi def source to use for comparison.

By the way, I don't have a power conditioner/surge protector hooked up yet but will soon. Thanks for any thoughts/insights.
Most likely it's that old problem- inconsistent digital cable signal.

Do you have a DVD player hooked up? If so, is that picture as good as you'd expect? If so, that rules out any panel issues.

You can call your cable company- or get DirecTV or Dish :)
Thanks Danlib. I do have a DVD player but haven't watched any movies on it except cartoons for the kids, so I don't have a good reference for comparison. I'll try a couple movies and see if anything looks amiss.

I'd love to try satellite, but too many trees around.
Digital TV is compressed. Some of it is good some is bad. Chances are you are not looking at an uncompressed HD quality picture like you would get from a BD player (so you see artifacts from compression or worse you are actually watching an upconverted 240 signal - half the resolution of DVD or what used to be normal TV in the olden days).

Also what are the pixels on your Panasonic - is it indeed true HD (1980 x 1020 pixels or 1080p) - most of the very best TV transmission are no better than 720 at the moment anyway.

Chances are is is the quality of what is being sent to you that is variable and which is causing variations in image quality. With 1080p you can really tell the quality of each program - some BD's in 1080 P are lousy and some - like Planet Earth BD are exceptional.
BTW, Soix, if you live in a climate with much snow or ice or heavy rain, you would find that satellite has its drawbacks!
I switched back to cable. Quality varies significantly from channel to channel but so does satellite.
Thanks guys.

Just to clarify, I've been watching the same HD cable channels including watching the Mets' annual swoon and the grainy quality is consistent across all HD channels. Normally the channels vary from good to very good (Mets games in particular look very good) to the point where they yield that "looking out a window" experience, but that is gone as of the past few days. And yes, my plasma is 1080p so fortunately I get to see the full reduction in my picture quality.

I called my cable company last night and found out my cable signal is on the weak side, so I'm hoping that turns out to be the culprit (that or a bad cable). Of course being home from 8 to 4 during the week to get it fixed is a bit of a problem. He all but laughed when I asked for a Saturday or Sunday appointment. I love cable.

Swampwalker -- I've seen the effects of clouds/snow/rain on satellite at my brother's in Annapolis and my friend's in Chicago, and it was all too frequent and not fun. My brother also ditched satellite because of it. Thanks for reminding me, but we're surrounded by huge trees so it's not even a possiblity (none of my neighbors have satellite either).

I'm seriously thinking of giving Fios a try. I know they have their service issues as well, but from what I've seen their picture quality seems pretty good. I'm a little concerned about their internet service though, and I'm not sure switching from a cable company to a phone company will make me better off overall. Any thoughts/experiences with them vs. cable?
Check your coax cable to be sure it is at least rg61. If you have old rg59 cable the picture really suffers...
Thanks for the info Winoguy -- I had no idea. How can you tell which you have? Is it labeled somewhere?
Well, this weekend my picture returned to "it's like looking out a window" performance and all seems right with the world. I turned off and rebooted my computer, which runs off the same cable, but I can't say if that did it nor do I know if that should have any effect on my TV's performance. Curious that my computer said other people were signed onto my computer when I was signing off (which is bothersome by itself), so I'm also wondering if that was eroding my cable signal. I'll ask the cable company, but I'll probably get some made-up answer from someone who knows nothing.

Thanks again for all the help, and I'll report back if I ever find the cause in case it might be helpful to others in this situation.

Still would like to hear from any Fios users on their opinions of that service.