Help me guys regarding my site serp

I have a site that ranks no 3 or 4 for a particular keyword between monday to thursday but vanishes from the top 1000 for the next 3 days then it again happens the same way next week.I am not sure what the problem is.It has a good backlink count(around 500).So please help me why is this happening.

any opinions??suggestions?

when was your site indexed man?

If this has been happening for a while then it's very unusual but there could be some possible explanations. Is there any change in the SERPs other than the disappearance of your site or is this an isolated problem? How often do you update the site and does the change in SERPs correlate with changes in your site content? Try to get an idea of how often the Googlebots visit to search your site (look at your server logs or other tracking tools) and check if there a connection with the timing you mentioned. Check your backlinks to see if there is any change between when you're in the SERPs and when your are not (especially the backlinks with the highest PR and the ones with site content/anchor text related to the keyword you're concerned about). Monitor your site to make sure there aren't any server problems, look at the robots.txt and htaccess files too. Change the passwords for your hosting account and any ftp accounts. You could even try moving to a different host if hacking is a concern.

thanks guys...
@psychul my site is more than 3 months old..it ranked 4th for the last 2 months..this is happening for the past one month....
@shockwave
I checked the backlinks..no change checked in them..i have also checked the above mentioned things..no notable changes..is this one assosciated with google dance??

sudarshannus said:

is this one assosciated with google dance??

Click to expand...

Google Dance can cause deviations between results but it shouldn't be as extreme as yours. There are some websites that will let you check your rankings on all of the Google data centers at the same time, you could try them to see if that's the problem.

Is it all SERPS or just google? What's your server uptime like? Do you have a dedicated IP or shared?

I agree with shockwave, the fact that the drop is so drastic and to happen only on weekends doesn't seem to be the typical google dance. To me that would be a +-10 not 1000.