I haven't installed that many mods:
Active Mod Files:00 Oblivion.esm01 Francesco's Leveled Creatures-Items Mod.esm [Version 4.5b]02 Francesco's Optional New Items Add-On.esm [Version 4.5b]03 Mart's Monster Mod.esm [Version 3.7b3p3]04 Unofficial Oblivion Patch.esp [Version 3.3.3]05 Improved Water.esp06 Enhanced Economy.esp [Version 5.1]07 Francesco's Optional Chance of Stronger Bosses.esp08 Francesco's Optional Chance of Stronger Enemies.esp09 Mart's Monster Mod for Fran.esp [Version 3.7b3p3]0A Mart's Monster Mod - Additional Enemy NPC Vars.esp [Version 3.7b3p3]0B Mart's Monster Mod - Hunting & Crafting.esp [Version 3.7b3p3]0C Mart's Monster Mod - Less Reavers.esp [Version 3.7b3p3]0D Mart's Monster Mod - Safer Roads.esp [Version 3.7b3p3]0E Mart's Monster Mod - More Wilderness Life.esp [Version 3.7b3p3]0F Mart's Monster Mod - City Defences.esp [Version 3.7b3p3]10 Mart's Monster Mod - Friendlier Factions MMM+Fran.esp [Version 3.7b3p3]11 Mart's Monster Mod - Farm Animals.esp [Version 3.7b3p3]12 Mart's Monster Mod - Diverse WaterLife.esp [Version 3.7b3p3]13 RealisticLeveling.esp14 Harvest [Flora].esp [Version 3.0.0]15 Bashed Patch, 0.esp
But in two occasions I have experienced said error whilst resting and have only played for 24 in-game days. Is that to be expected?