Does my website get effected by sites in same server

Hi DPers,

My blog is hosted in shared host with 250 other sites in the same server and i wonder if those 250 can effect or play with my rankings. The reason i ask is last night Google indexed urls in my blog that i requested indexing for, also the imgs in urls indexed are in image search, however those same urls got deleted today with the imgs too, leaving me with stat before the indexing.

Any suggestions?