Can someone test false positive for HIV in the window? How often does a false positive occur?!?

They said the initial test, Elisa tested positive twice for antibodies--- and it is tested twice due to the extreme sensitivty of the test then i was confirmed by a western blot which turned out to be negative? explanation???

Elisa has a 3-10% probability of a false positive. The Western blot is considered the best test but even it relies on the judgement of the test reader looking at the bands or rather looking for the bands.

So it is possible that you got two false positives on teh Elisa, but is also possible that you are positive and the person misread the Western blot test. As a measure of safety, and since you already have two positives, I would suggest another Western blot in 1 to 2 months and suggest it be done by a different lab.

The real question is why you are worried, are in a high risk group? If so then most certainly get recheck later. If your not in a high risk group then don't worry too much now but still get rechecked later.

Its difficult to quantify what a false negative probability is for any test as it is always possible that the evidence of infection your looking for aren't in a great enough concentration within your body to show up.

Sort of like testing for pregnancy each day after you had sex. Even though you conceived you wont show up on some test until you have actually been pregnant for some time. Does that mean that your pregnancy tests were false negatives? No it simply means that the chemical marker you were looking for wasn't picked up even though it was there.

This barely ever happens ever. This is very unusual and you should not worry about it.

Two separate tests are performed when screening for HIV in a laboratory. The ELISA test and the Western Blot. They each have features that make them extremely efficient in making sure that someone is not misdiagnosed.
The ELISA test is the "screening test" while the Western Blot is the "confirmatory test".
When blood reaches the lab, an ELISA test is performed. If the ELISA is negative, you are HIV-. This test is prone to "false positives" in fact it errs on the side of positive, so a negative result is considered conclusive.
If there is a positive ELISA or and "indeterminate" reading from the ELISA, then the confirmatory testing is done (Western Blot).
The Western Blot test is much more specific and the chances of getting a false positive are EXTREMELY rare. This test is much more expensive than the ELISA so they use the ELISA to screen out most of the negatives.
So, together they act as a catch all and they are very accurate. What happened to you happens a lot. Most people don't look at the specifics of the test results other than to hear "positive" or "negative".
Nothing out of the ordinary.
Hope this helps