when i try install openjdk-7-jre-headless i am getting the following error:

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  ca-certificates-java icedtea-7-jre-jamvm java-common libcups2 libjpeg62 liblcms2-2 libnspr4 libnss3 libnss3-1d openjdk-7-jre-lib tzdata tzdata-java
Suggested packages:
  default-jre equivs cups-common liblcms2-utils libnss-mdns sun-java6-fonts ttf-dejavu-extra ttf-baekmuk ttf-unfonts ttf-unfonts-core ttf-sazanami-gothic
  ttf-kochi-gothic ttf-sazanami-mincho ttf-kochi-mincho ttf-wqy-microhei ttf-wqy-zenhei ttf-indic-fonts-core ttf-telugu-fonts ttf-oriya-fonts
  ttf-kannada-fonts ttf-bengali-fonts
The following NEW packages will be installed:
  ca-certificates-java icedtea-7-jre-jamvm java-common libcups2 libjpeg62 liblcms2-2 libnspr4 libnss3 libnss3-1d openjdk-7-jre-headless openjdk-7-jre-lib
  tzdata-java
The following packages will be upgraded:
  tzdata
1 upgraded, 12 newly installed, 0 to remove and 122 not upgraded.
Need to get 41.2 MB/43.5 MB of archives.
After this operation, 64.0 MB of additional disk space will be used.

Get:5 http://in.archive.ubuntu.com/ubuntu/ oneiric/main java-common all 0.42ubuntu2 [62.4 kB]
Fetched 41.1 MB in 4min 5s (167 kB/s)
Failed to fetch http://in.archive.ubuntu.com/ubuntu/pool/main/j/java-common/java-common_0.42ubuntu2_all.deb  Size mismatch
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

am unable to solve this. Am i missing something? please help me out in solving this.