I bough a new scandisc sdhc card but when inserted and turned on the sreen after a few seconds shows 'memory card error'. what would be wrong here?

Does the camera accept SDHC cards (which is what you have)? if not that is the problem.

When the card worked before, check if you did not switch the lock switch down. And check all contacts on the card and in the camera. They should be clean and shiny.
When you recently bought a new card you could have bough a SDHC card and these won't work in your S800.
The S800 only accepts MMC and SD cards, The SDHC and SDXC cards won't work.
A few years ago you still could buy 4 Gbyte SD cards. Now even most 1 Gbyte and 2 Gbyte cards are already SDHC. SDHC was introduced at least 7 or 8 years ago, so all new devices accept SDHC. The SDXC was introduced at least 4 years ago, so in a couple of years, you perhaps only can buy these cards?

Clear it by putting in a compatible memory card. The S1030 works with SD cards. Your 8GB SDHC card in not compatible. You need to use SD cards, 2GB and smaller.

There are several possible causes for "memory card locked", "memory card error", or "no memory card". The most common cause is having the tiny slide switch on the side of the card in the wrong position. The second most common is trying to use a 4GB or higher SDHC card with an older camera made before SDHC format came out. Please note that your particular model camera can only use up to 2GB standard SD cards. These are relatively inexpensive these days, and may be purchased on Amazon if your local store no longer carries them. There are also other common causes if the above didn't help, with troubleshooting steps for this problem listed here.

There are several possible causes for "memory card locked", "memory card error", formatting problems, or "no memory card". The most common cause is having the tiny slide switch on the side of the card in the wrong position. The second most common is trying to use a 4GB or higher SDHC card with an older camera made before SDHC format came out. There are also other common causes if the above didn't help, with troubleshooting steps for this problem listed in this linked article.

There are several possible causes for "memory card locked", "memory card error", or "no memory card". The most common cause is having the tiny slide switch on the side of the card in the wrong position. The second most common is trying to use a 4GB or higher SDHC card with an older camera made before SDHC format came out. There are also other common causes if the above didn't help, with troubleshooting steps for this problem listed here.

The largest SD card you can use in your Samsung NV10 is 2GB. thats why once you insert the 8GB sd card its shows card error or need to fromat.

FYI. for every digital camera there's a compatible memory card and you can see from the box or manual and Its writen SD or SDHC.

goodlukc and thank you

There are several possible causes for "memory card locked", "memory card error", or "no memory card". Some include trying to use of a 4GB SDHC card with an older camera made before SDHC format came out. Others include problems with the tiny slide switch on the side of the card, or the electrical contact switch internal to the camera. The problem may also arise from simple formatting problems if the card has never been formatted in the camera (note that this will also erase the card). Troubleshooting tips for this problem may be found at this link.

I'm guessing you bought a new 4GB SDHC card. Although it looks exactly the same as a standard SD card, the format the card uses is very different. If your camera is more than a few couple years old, it's likely it was designed before the SDHC format came out. Sorry, but a SDHC card will not work with older cameras.
For older cameras, you'll need to use standard SD cards (usually those 2GB or less). But if you really want to use a 4GB card, do a Google search for 4GB SD "non HC", with the non HC in quotes. Believe Transcend makes one.

If all other cards work fine then you may have a faulty memory card.

Your camera should theoretically be able to handle an 8GB SDHC card (but only up to 2GB xD card) as it is an SDHC compatible camera, but I've encountered more than a few cameras in the past which were SDHC compliant but could only handle up to 4GB.

Most of these had firmware updates to enable up to 16GB SDHC but the Fuji S1000fd has no firmware update.

If you find that the SDHC card is fine after all then I'd suggest contacting Fuji for a definite say so as to whether they know of any issues with 8GB SDHC compatibility.