Occcasional WiFi Instability
Use a program such as inSSIDer to see what other strong wireless are around that could interfere with your own. Look for overlapping channels and if there are any try to change to a "quieter" channel.
The latest version is no longer free so here's an earlier free one:
inSSIDer 3.1.2.1 Download - TechSpot
The latest version is no longer free so here's an earlier free one:
inSSIDer 3.1.2.1 Download - TechSpot