Problems with wireless and Symantec

[KatzenFrau]

We travel often and use many unencrypted wireless networks on an XP laptop using Norton Internet Security. Very often the Symantec updates are corrupted and/or corrupt OE. The only fix is to reinstall Norton, often several times. At home we run the XP laptop, and a destop ME on cable highspeed with a Belkin pre-N, WEP encrypted network. Both have suffered corrupted files, and the ME is not responding to a reinstall. A desktop XP, also networked, updates Norton by dialup and has had no problems. Is this common? Happening to others? Suggestions for good security software that works well with wireless?