Yes, those blocks I mined do not give me any rewards, even though I worked on them.
I use GUIMiner.
102 Mhash/s.
It is possible slush's pool didn't mine those blocks.
With pooled mining, all the people who helped get paid when a block is mined.
If the block doesn't get mined by the pool, nobody who worked on that block gets paid.
You have a really small amount of hasing power.
I have a 336Mhash usb block eruptor(it is also very small hashing power comparitively)
it makes me 0.00022225 per 24 hours on BTC Guilds pay per share.
I would advise you simply stop mining, the strain/decreased lifespan of your gpu is not worth the pennies of BTC you will make.