Might be a couple of things. First, there appear to be many variations of the ‘555’ and although they should functionally work the same, the circuitry inside is different and can cause many different types of problems. A lot of 555 chips may have what is known as a totem pole output where there are 2 transistors, stacked one on top of the other, between the + and – supply with the output from their common junction. This configuration allows the 555 to either source or sink current. There is an extremely small moment of time when switching that both transistors could be on, producing a short and having a large current flowing through the transistors. The way around this is to wire a, say 22 ohm, bypassed resistor in series with the + for the 555 to limit the current to a safe value.
The second problem is somewhat related to the first and relates to the NE555 you are using. Here is an answer to a question I found on line.
“You've discovered one of the best kept secrets of the 555. That is, they aren't all the same. In fact, I know which one you have. It's the NE555 from Texas Instrument (silver top, right?), because that's what RadioShack stocks even though the catalog says LM555. The difference is that the LM555 is a bipolar chip and the NE555 is a CMOS chip. And I bet that pin 2 of this circuit is waving in the air — picking up static electricity. When the first CMOS 555s showed up on my workbench, I had the same problem until somebody told me they were CMOS, then the light went on. When working with CMOS technology, every pin has to go somewhere, used or not. What you need to do is tie pin 2 high through a 10k resistor, that's pretty close to its bipolar equivalent, and the circuit will work.”